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By V. K. Kuppusamy, M. Holuszko

"Lamps and lighting products are the most commonly used electrical products around the globe. With the improvement in lamp technologies, lighting products have grown complex and hence require an improved recycling process. The LED lamps consist of various valuable metals such as iron, copper, aluminum, chromium, silver, and gold, as well as non-metals such as glass, plastics, and fibers. In addition, there are also traces of hazardous substances such as lead, arsenic, and mercury. A major step in the recovery process is size reduction, and researchers have suggested that up to 40% of the total valuable material is lost during the shredding and grinding processes. SELFRAG is a high voltage selective fragmentation comminution technology that uses high voltage pulses in a water medium to efficiently separate the metals at a coarser size without generating many fine particles. It has been proposed that during the fragmentation process of electronic waste (e-waste), the metals can be separated without fine grinding. This research considers the applicability of high voltage pulse fragmentation for LED lamps. Eight different types of LED lamps were processed through the SELFRAG unit at varying pulses to study metal liberation. The product obtained was characterized for metal liberation, metal grades, and liberation analysis. The specific energy consumption for this size reduction process was also monitored. INTRODUCTION Lamps and bulbs are the most commonly used electrical products in homes, offices, industrial operations, and streets. According to Energy Star research (2006), an average US household has more than 40 sockets for light bulbs and consumes approximately 2100kWh every year for lighting. The development in lamp technology has pushed the boundary for newer products. The LED lamps have been taking over the market from the incandescent bulbs and compact fluorescent lamps (CFL). According to the US Department of Energy (2012) and myLEDlight.com (2007), LED lamps have several benefits over other lamps. LEDs produce light hemi-spherically, which increases their efficiency in directional light emission. It has higher breakage resistance from vibration or transportation. LED lamps use up to 90% less power than incandescent bulbs thus making them highly energy efficient; They have a longer lifespan, lasting 10 times longer than a CFL and 133 times longer than the traditional incandescent bulb. Because of all the benefits, Smallwood (2014) suggested that the market of LED lamps will grow to $12.2 billion by 2018."

Jan 1, 2018

By Chuanyao Sun, Longli Liu, Fayu He, Guiye Wu

Utilizing thioglycolic acid (TGA) as a template and using structure-guided design, a molecular modelling approach has been used to design and screen appropriate dispersant for chalcopyrite. A series of organic dispersants based on a TGA substitution with hydroxyl and amino and sulfonic functional groups have been examined on chalcopyrite surface. 20 organic depressors of chalcopyrite have been investigated to study the quantitative structure-activity relationship (QSAR) of chalcopyrite depressors. For the chalcopyrite surface, depressor containing carboxyl and sulfonic group is generally stronger than the depressor containing hydroxyl group. Increasing the number of hydrophilic group can effectively enhance the inhibition. Increasing the number of Solidophilic group does not necessarily lead to enhanced inhibition ability; steric factor is one of the important factors to affect the interaction. Extension alkyl carbon chain length cannot enhance the interaction of depressors. Isomers principle as well as applies to the chalcopyrite depressor molecular design. Flotation verification tests further confirmes the accuracy of the molecular simulation. Through the Computer Aided Molecular Design (CAMD) technology, we can save enormous time and resources to design novel surfactants. This research and application will play a great significance role in sulfide flotation.

Jan 1, 2014

By Kunihiko Yamaguchi, Gjergj Dodbiba, Toyohisa Fujita

Usually magnetic separation is performed to separate ferromagnetic, paramagnetic and diamagnetic particles by controlling magnetic field strength. In this research the wet high gradient magnetic separation at various kinds of magnetization of medium has been investigated to separate different kinds of magnetization of paramagnetic mineral particles from each other. Most of week paramagnetic particles are captured at high magnetic field using superconducting magnet. If the magnetization of fluid is larger than that of paramagnetic particle, the paramagnetic particle cannot be captured in the direction of magnetic field. The paramagnetic particles of different magnetization such as hematite, chromium oxide, perovskite and rutile are separated in different magnetization of fluids. These particles are present in the incinerated bottom ash. The separation is useful to recover titanium oxide from bottom ash and the removal of chromium of bottom ash is important to reuse the bottom ash as cement. The used fluids are paramagnetic liquids dissolving paramagnetic salts and the water based magnetic fluid dispersing the stable ultrafine magnetite. The dispersion condition of particles related to zeta-potential of the suspension feed is also important to separate effectively by controlling pH

Jan 1, 2014

By Marco Le Roux, Quentin Campbell

"Most coal supply contracts include strict limitations on the moisture content of the products. This limitation exists because of calorific, transport cost, and handling reasons. Managing the retention time on product stockpiles to facilitate drainage commonly controls the moisture content in coarser coal products. A large-scale pilot rig has been commissioned to facilitate research in this regard. A stockpile of about 15 tonnes of a typical washed power station feed coal from the South African Witbank coalfield was loaded onto a 6 x 6 m platform on load cells. The platform was shielded from the elements, like rain and wind, and an artificial rain sprinkler system was installed. A variety of rainfall intensities and durations were simulated and the water accumulation and run-off was measured. The material was also sampled for moisture and particle size before and after the series of tests. At the same time, the drainage characteristics of the same coal were determined in smaller scale drainage columns for comparison. Data is presented in this paper on the drainage rates, maximum accumulated moisture, final moisture, and the effect of evaporation. The results showed that for all rainfall patterns tested, drainage ceased after 2 - 3 days, but evaporation continued for at least the time period under investigation, albeit at a low rate. Evaporation contributed to dewatering at rates that depended on wind, temperature and humidity conditions. This caused a slow reduction in moisture content even after the run-off had ceased. The value of the final moisture depended on the coal PSD. It was also found that the intensity and duration of the more intense rainfall events did not significantly affect the maximum water accumulation, with drainage rates equaling the corresponding water addition rates which suggested that water ran off over the surface of the stockpile with limited penetration. During more intense rainfall scenarios, some penetration was apparent."

Jan 1, 2014

By Mahdi Shevrini, Hamed Haghi

"In this research, the operation of screen classifying in silica processing circuits was investigated and modified by replacement of available trommel screens with teetered bed separator (TBS). In addition the effect of the mentioned replacement and addition of attrition scrubber on quality of final product, impurities removal, recovery and production rate were inspected. Considering screen efficiency problems to achieve certain particle size distribution, hydraulic classifying system was selected instead of trommel screens. Application of suggested plan improved quality and particle size distribution of produced silica significantly. Optimization of size classification in process circuit resulted in increase in production rate up to 21% (from 67% to 81%), silica recovery (from 68.35% up to 83.11%) and relative enhancement in removal of impurities such as Fe2O3 and TiO2. After optimization and stabilization of grinding and size classification section, industrial attrition scrubbing tests were carried out and the best solid percent and retention time were determined i.e. 70% and 6 minutes, respectively. Using sodium carbonate during attrition scrubbing, has major effect on removal of surface coating and staining especially sharp increase in clay removal; therefore 2 kg/t of sodium carbonate can be optimistic point of industrial procedure for this silica processing plant. It should be mentioned that application of attrition scrubbing which is followed by screw classifier for de-sliming were useful for better cumulating of particles in the range of appropriate liberation degree (+106-300µm) and efficient removal of metallic (iron and titanium oxides) and non-metallic (clays and feldspars) impurities."

Jan 1, 2014

By Ronel du Plessis, John C. Davidtz, Jan D. Miller

Xanthates (dithiocarbonates) have been the collector of choice for the flotation of sulfide minerals ever since the flotation process was developed and have been studied quite extensively. Recently, trithiocarbonates have been shown to be very effective in bulk sulfide bench-scale flotation. Fundamental analysis using electrochemical techniques have supported these bench-scale results, illustrating that the trithiocarbonate (TTC) collectors are more readily oxidized to their corresponding dithiolates, than the dithiocarbonate (DTC) collectors, as is shown in Figure 1.

Jan 1, 2003

By G. S. Hansford, G. E. Searby

The rate of bioleaching of pyrite at 70ºC by a thermophilic archaeal culture was measured as a function of the solution redox potential by the staged addition of pyrite to a batch system. The results were compared to the rate of ferrous iron oxidation over the same potential range to determine the applicability of the multi-sub-process leaching mechanism developed for mesophilic bioleach systems.

Jan 1, 2003

By A. Boulton

Low molecular weight synthetic polymers substituted with hydroxyl, carboxyl or sulfonate functional groups were used to improve the flotation separation of zinc or copper sulfide minerals from iron sulfide gangue minerals in three massive sulfide ores of different mineral composition. These polymers produced significant improvements in zinc or copper grades as a result of a selective depression of iron sulfide minerals. These results are significant considering the differences in ore type, proportion and type of iron sulfide minerals present, and grinding medium used in this study.

Jan 1, 2003

By C. Abbruzzese, F. Vegliò, S. Ubaldini, R. Massidda

The aim of this paper was to study the influence of different water/organic solvent mixtures (isopropyl alcohol, ethanol and ethylene glycol) on the gold desorption process. The experimental work was carried out on laboratory scale, using activated coconut carbon with different temperatures and extraction times, without adding cyanide. Best results have been obtained in this order: isopropyl alcohol > ethylene glycol > ethanol. Starting from gold concentration of about 5 g Au per kg of carbon, best kinetics resulted in 97-100% of gold extraction, after 8 hours of desorption, at a temperature of 80ºC.

Jan 1, 2003

By Nóra Schreithofer, Kari Heiskanen

"INTRODUCTIONThe knowledge of the adhesion forces between particles and bubbles is of key importance in the improvement of flotation models. The development of the Colloidal Interaction Force Measurement Apparatus (CIFMA) opened the possibility to quantify the adhesion forces between particles and bubbles. The aim of this study was to examine the effect of three main variables: the approach velocity, the loading force and the loading time on the adhesion force between an air bubble and a hydrophobized silica particle."

Jan 1, 2003

By Jussi Liipo, Pertti Lamberg

Image analysis of process samples gives precise data on particles and their composition. The results presented as liberation tables and maximum grade-recovery curves are informative and good for comparing different feed materials, but basing on them it is impossible to predict the results of the mineral separation process (flotation, magnetic separation, gravity separation) in details. The exact and extensive particle data has remained large unused, because there has not been a model nor a modeling program to include particle information in mineral separation processes. This study introduces a method, which incorporates the particle data in the kinetic model of flotation. Similar approach can be used in modeling other separation processes, too.

Jan 1, 2003

By Peter Ay, Matthias Schmidt, Christian Stollberg

"The aim of the study is the development of a seamless reprocessing procedure for plastics from automotive parts which are to be recycled (figure 1). Before automatic sorting can be performed, the materials first have to be identified by a near and middle infrared (NIR/MIR) system.Materials reprocessing basically includes research on size reduction, decoating, and roughening of the materials. Variants of the necessary technologies such as different shredders and mills and physico-chemical or mechanical decoating and roughening procedures together with the fundamental approaches underlying these methods are investigated and benchmarked. This allows the theoretical determination of the impact of each method not only on the overall process but also on the result achieved within the identification and sorting procedures."

Jan 1, 2003

By Masakazu Niinae, Kenji Aoki

"Electrokinetic soil remediation by electroosmosis and ionic migration is restricted to soluble substances. At a higher pH, the soil particles sorb more heavy metals than at a lower pH and the precipitation of heavy metals are promoted. Both mechanisms make heavy metals immobile, rendering cleanup more difficult and electrokinetic extraction inefficient.In this study, the effectiveness of introducing a complexing agent to enhance the removal of cadmium from kaolinite in the region of neutral pH by ionic migration is examined. The complexing agent selected was ethylenediaminetetraacetic acid (EDTA). The investigation was carried out in a laboratory-scale column containing kaolinite contaminated with cadmium. As the results of the study, cadmium migrates toward the anode without accumulation of cadmium and is successfully removed at the anode reservoir."

Jan 1, 2003

By Willis Forsling, Prabhakar Swarna, Hanumantha Rao Kota

"The solubility of wollastonite and its Hallimond flotation behavior as a function of dodecylamine concentration and pH are examined. The flotation response is characterized by adsorption and surface energy in the presence of amine. The methods of UV-Visible and FT-IR spectroscopy for adsorption and sessile-drop contact angle for surface energy estimation are employed.The results of wollastonite dissolution clearly showed its non uniform dissolution. The surfaces are depleted with calcium ions and became rich in silicon within 10 min of flotation time. Maximum flotation of wollastonite corresponds to a half monolayer coverage of amine, which is substantiated by the surface energy parameters as shown in figure 1."

Jan 1, 2003

By Rainer M. Lotzien, Michael J. G. Battersby, Jan Kleefeld, Julian V. Brown, Rainer M. Imhof

A new flotation system has been developed to improve the generally slow separating differentials of fine bubbles and fine particle suspensions. The new technology is based on established pneumatic flotation designs called Imhoflot which use intensive in-line pre-aeration to aerate the flotation pulp prior to its introduction to the separating cell. In the new system (see figure 1) this separation is speeded up dramatically by the introduction of centrifugal motivation in the separating vessel, without the use of internal moving parts. The design focuses on providing increased differential forces on buoyant mineralised bubbles and hydrophilic fines. The commercial benefit to industry is much reduced residence time, less than 30 seconds, which offers considerable cost savings in equipment and infrastructure.

Jan 1, 2003

By R. Peter King, Claudio L. Schneider, Reiner Neumann

Predicting the liberation spectra that is produced from breakage of two-phase ores under the random fracture assumption can be accomplished by measuring the conditional, on length, linear grade distribution directly from images obtained from a representative sample of the unbroken texture. The technique tremendously simplifies the prediction problem by avoiding the multiple convolutions that arise from the traditional method based on a description of texture from a measurement of the chord length distributions associated with each phase in the unbroken texture. For a 3-phase system, the phase transition probabilities associated with the textural information make the traditional calculation an almost insurmountable mathematical problem. The direct measurement procedure on the other hand can be expanded to three phases comparatively easily.

Jan 1, 2003

By Markus A. Reuter, Antoinette van Schaik

"INTRODUCTIONGoods and products, such as passenger vehicles, are manufactured by using a wide spectrum of different raw materials to meet highest consumer requirements during use. Due to the time-varying composition and complexity of multi-component products such as cars, recycling is complicated. It involves a network of interconnected processes and material and energy flows. Improving the efficiency of the material cycle of the car to comply with the recycling targets as imposed by EU legislation, requires insight into all aspects influencing the closing of the material cycle (dynamics, technology, economy, legislation, etc.) and their mutual relation. In order to define the link between recycling end-of-life products, their changing composition and design a dynamic model was developed for the resource cycle of cars. The model integrates the optimisation of the material cycle with the dynamic behaviour of recycling systems."

Jan 1, 2003

By R. Els Ellis

Enhanced granulation of UASB granules was tested on pilot scale with two different test reactors (about 5 litres capacity each). Sludge from a local sewage works was used, with peach cannery effluent as carbon source. Cyclic motion of the reactor contents, and a daily replenishment of feed material create the necessary stress conditions for enhanced growth. Sizable granules, bigger than 0.5 mm, were produced within 20 days. Of the two reactors tested, the reactor equipped with a horizontal agitation shaft proved more effective.

Jan 1, 2003

By Markus A. Reuter, Yongxiang Yang, Jim R. Post

In the upper part of an iron making blast furnace, sinter, coke and pellets are charged. While descending, the burden is heated and the iron oxides are reduced by the rising gases. The iron oxides start to soften and eventually melt. The melt and the remaining coke collect in the lower part of the blast furnace: the hearth. The remaining coke forms a porous bed: the dead man (see Figure 2). The melt flow through the dead man can affect substantially the hearth lining life, the furnace productivity and product (i.e. hot metal) quality. Physical characteristics like porosity and particle size distribution of the porous coke bed play a critical role. Because of the distributed nature of the coke properties, the bed packing structure and porosity will not be constant.

Jan 1, 2003

By Jan Svoboda, Atsushi Shibayama, Toyohisa Fujita, Toshio Miyazaki, Kenji Murata

"The electrical disintegration (ED) method and disintegration by underwater explosion were investigated as new fragmentation techniques for the kimberlite ore and tungsten scrap of superalloy (carbide bit). The results of various breakage tests demonstrated that both fragmentation methods as new disintegration techniques for recycling were able to liberate various components of materials of different resistivity and elastic impedance.SUMMARYThe breakage of the kimberlite ore from South Africa (sample size: 15 mm x 15 mm x 6 mm) was achieved by the ED method. A relationship between the sample size, voltage, the electrical current and the energy needed for the disintegration was found from the experimental results. Kimberlite exhibited a high degree of breakage, when the high voltage of 60 kV and the pulse current of approximately 5000 A were applied to the sample by the generator during 0.2 microseconds (Fig. 1)."

Jan 1, 2003