high end small glass rod mill sell at a loss in abuja

bioelectricity generation from palm oil mill effluent in microbial fuel cell using polacrylonitrile carbon felt as electrode | springerlink

bioelectricity generation from palm oil mill effluent in microbial fuel cell using polacrylonitrile carbon felt as electrode | springerlink

Palm oil mill effluent (POME) is an organic waste material produced at the oil palm mills. In its raw form, POME is highly polluting due to its high content of biological and chemical oxygen demand. In the present paper, POME was treated using double chamber microbial fuel cell with simultaneous generation of electricity. Polyacrylonitrile carbon felt (PACF), a new electrode material was used as electrode throughout the MFC experiments. Various dilutions of raw POME were used to analyze the effect of initial chemical oxygen demand (COD) on MFC power generation, COD removal efficiency and coulombic efficiency. Anaerobic sludge was used as inoculum for all the MFC experiments. Since this inoculum originated from POME, it showed higher potential to generate bioenergy from complex POME. Anaerobic sludge enhanced the power production due to better utilization of substrates by various types of microorganisms present in it. Among the raw POME and different concentrations of POME used, the PACF with raw POME showed the maximum power density and volumetric power density of about 45mW/m2 and 304mW/m3, respectively, but it showed low coulombic efficiency and low COD removal efficiency of about 0.8% and 45%, respectively. The MFC PACF with 1:50 dilution showed higher COD removal efficiency and coulombic efficiency of about 70% and 24% but showed low power density and low volumetric power density of about 22mW/m2 and 149mW/m3, respectively. The formation of biofilm onto the electrode surface has been confirmed from scanning electron microscopy (SEM) experiments. The results confirm that MFC possesses great potential for the simultaneous treatment of POME and power generation using PACF as electrode and also shows that initial COD has great influence on coulombic efficiency, COD removal efficiency and power generation.

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Kim, G. T., Webster, G., Wimpenny, J. W., Kim, B. H., Kim, H. J., & Weightman, A. J. (2006). Bacterial community structure, compartmentalization and activity in a microbial fuel cell. Journal of Applied Microbiology, 101, 698710.

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Liu, H., Cheng, S. A., & Logan, B. E. (2005). Power generation in fed-batch microbial fuel cells as a function of ionic strength, temperature, and reactor configuration. Environmental Science and Technology, 39, 54885493.

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Pham, T. H., Rabaey, K., Aelterman, P., Clauwaert, P., DeSchamphelaire, L., Boon, N., et al. (2006). Microbial fuel cells in relationtoconventional anaerobic digestion technology. Engineering in Life Science, 6, 285292.

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Baranitharan, E., Khan, M.R., Prasad, D.M.R. et al. Bioelectricity Generation from Palm Oil Mill Effluent in Microbial Fuel Cell Using Polacrylonitrile Carbon Felt as Electrode. Water Air Soil Pollut 224, 1533 (2013). https://doi.org/10.1007/s11270-013-1533-1

chemical composition of processed bamboo for structural applications | springerlink

chemical composition of processed bamboo for structural applications | springerlink

Natural materials are a focus for development of low carbon products for a variety of applications. To utilise these materials, processing is required to meet acceptable industry standards. Laminated bamboo is a commercial product that is currently being explored for structural applications, however there is a gap in knowledge about the effects of commercial processing on the chemical composition. The present study utilised interdisciplinary methods of analysis to investigate the effects of processing on the composition of bamboo. Two common commercial processing methods were investigated: bleaching (chemical treatment) and caramelisation (hygrothermal treatment). The study indicated that the bleaching process results in a more pronounced degradation of the lignin in comparison to the caramelised bamboo. This augments previous research, which has shown that the processing method (strip size) and treatment may affect the mechanical properties of the material in the form of overall strength, failure modes and crack propagation. The study provides additional understanding of the effects of processing on the properties of bamboo.

Fibre reinforced composites are ubiquitous with uses in a variety of industries, including the automotive and infrastructure sectors. Synthetic fibres (such as glass, carbon, and aramid) embedded within a polymer matrix provide improved performance without increasing weight. While man-made composites dominate the market, there is growing interest in the use of renewable materials. Bamboo grows as a natural fibre composite with potential to be an alternative to conventional materials. The use of natural composites has multiple advantages, including the potential for being light-weight and offering environmentally-friendly routes to end-of-life disposal. For example, bio-based matrices are oftendegradable and are also used in energy recovery. Design and processing are key in the development of composites, whether synthetic or natural, to meet the requirements for performance.

Laminated bamboo is an engineered composite that is primarily used as a surface material (e.g. flooring, furniture, architectural detailing). The material is being increasingly explored for structural applications, however products are adopting existing manufacturing methods, as shown in Fig.1. Although bamboo products are often compared to timber products, such as glue-laminated timber, the similarities are limited to them being plant-derived cellulosic materials. Reduced environmental impact is a major driver for use of laminated bamboo, with the cradle-to-gate production of a 19mm single-ply laminated bamboo panel generating approximately 1.0kg of carbon emissions per kg of product (kgCO2eq./kg), compared to 1.8kgCO2eq./kg for steel and 11kgCO2eq./kg for concrete (van der Lugt and Vogtlnder 2015). For comparison, primary production of glue laminated timber generates approximately 0.8kgCO2eq./kg (CES 2017). The additional processing required to manufacture the laminated bamboo panel increases the embodied carbon when compared to glue laminated timber.

Acommercial board product, laminated bamboo sheets consist of raw bamboo material that undergoes one of two treatment processes: bleaching or caramelisation (Fig.1). The choice of the process is dictated primarily by the colour preference for the surface material. In the bleaching process, the split and planed bamboo strips are bleached to a light yellow colour in a hydrogen peroxide bath at 7080C (van der Lugt 2008). In contrast, the caramelisation process uses pressurised steam at approximately 120130C (van der Lugt 2008), caramelising the sugars in the bamboo to obtain a deeper brown colour. The depth of colour differs based on the duration of treatment, which can vary from 4 to 8h (van der Lugt 2008). Commercially, the caramelised colour is preferred for surface applications. However, the effects of processing on the mechanical properties, if any, are unknown (Sharma et al. 2015). These processing methods are also used as a preservation treatment, removing the sugars and starches (Liese 1980) in the culm to prevent biodegradation. The low microbial resistance of natural fibres leads to degradation issues before processing, which is avoided in laminated bamboo through processing of the material within 23days of harvest.

Raw bamboo consists of cellulose, hemicellulose, lignin, ash and other extractives (Li 2004). The content varies between and within species and is dependent on the age of the culm, as well as the location along the height of the culm and within the culm wall (Li 2004). We note that the method of quantification itself may influence the amount of component quantified. For instance, with lignin Sluiter et al. (2010) track the evolution of the Klason protocol over the years and the difficulty to compare each other. Hatfield and Fukushima (2005) investigated the accuracy of lignin quantifications, by evaluating several methods. While we expect thermal treatment to alter the chemical composition of bamboo, the effects are yet to be characterised. Studies in existing literature primarily investigate compositional changes with thermal treatments in connection with the potential of bamboo for biomass, which are at temperatures substantially above those used in processing laminated bamboo, or when exploring non-structural applications of full-culm bamboo, such as for furniture. Bleaching with hydrogen peroxide is a process used in wood pulp and paper manufacturing, however the process has no precedent in manufacturing of structural bamboo materials.

Processing temperatures for plant-based materials are typically limited to 200C due to degradation of the fibres at higher temperatures (Jacob et al. 2005). In timber, thermal treatment is used to increase dimensional stability, reduce moisture content and improve durability. Thermal modification results in changes to the chemical structure and consequently mechanical properties (Tjeerdsma et al. 1998; Sundqvist et al. 2006; Poncsak et al. 2006; Kubojima et al. 2000; Hakkou et al. 2005; Campean et al. 2007; Bhuiyan et al. 2000). Some studies have reported that temperatures above 130C reduced the compressive strength of spruce, with the most significant degradation being the mass loss of hemicellulose, leading to a slight proportional increase in the relative ratio of cellulose and lignin at higher temperatures (Yildiz et al. 2006). The effect of thermal treatment on the chemical composition of wood also differs between species, with, for example, beech able to withstand temperatures up to 220C (Windeisen et al. 2007). Bamboos are wood-analogous materials in terms of their chemical make-up and similarly we envision the effects of preservation treatments to differ between species. The impact of steam treatment on the bending strength of hardwood species (such as black locust, oak, merbau, and sapupira) indicates thatproperties degrade above 100C (Varga and van der Zee 2008). To optimise the properties of the material, such as the dimensional stability and wettability, thermal treatment can be used, however the changes in chemical composition can affect the performance of the material in structural applications (Varga and van der Zee 2008).

Although biomass applications utilise temperatures above those used in laminated bamboo processing, studying the changes in composition occurring with thermal treatments is useful for understanding changes in physical properties of bamboo. Studies on bamboo charcoal have shown that the heat treatment of bamboo up to 200C degrades hemicellulose, and free water is generated due to chemical breakdown (Zuo et al. 2003). Duration of treatment also has an impact on the properties of bamboo with the strength and modulus of elasticity showing different tolerances to heat treatment, increasing up to 120 and 140C, before steadily decreasing (Zhang et al. 2013). The strength has also been shown to correlate with the mass loss due to thermal treatment arising from degradation of holocellulose and cellulose I (Zhang et al. 2013). Similar effects were noted in other species of bamboo with degradation occurring at increased temperatures and the effect of temperature was more significant than duration (Nguyen et al. 2012). The effect of thermal treatment increases dimensional stability, however excessive temperature and duration results in degradation at a micro-scale. The results suggest that heat treatment may be potentially tailored to alter the composition of the material for structural performance (Ramage et al. 2017). Our related work demonstrated significant differences in structural performance and failure modes (Sharma et al. 2015; Reynolds et al. 2016). The preservative treatments affected the load capacity and ductility before fracture in laminated bamboo dowel connections (Reynolds et al. 2016). The influence of the treatment methods on the microstructure of the material and crack propagation is not fully understood.

Further work assessed the influence of the strip size on the structural performance of the material (Penellum et al. 2018). Penellum et al. (2018) observed that the strip size, which results in an increase in the fibre volume fraction, correlates closely with the higher bending stiffness. The effect of the preservative treatment method on stiffness was unclear and more likely attributed to strip size (Penellum et al. 2018). The present study aims to clarify the effect of the changes in chemical composition of bamboo by two commercial processing methods (bleaching and caramelisation) on the resulting laminated bamboo products.

The study compared the chemical composition of raw, bleached and caramelised Moso bamboo (Phyllostachys pubescens). The raw Moso bamboo is smoke treated but not additionally processed; samples were obtained from the full culm wall thickness, with the age of the culm unknown, however the material was sourced from the same supplier. The sample preparation removed the waxy exterior and pithy interior to obtain the culm material similar to that used in the processed product. The bleached and caramelised bamboo material were manufactured commercially (Supplier: Plyboo) and obtained from laminated bamboo boards, made from raw Moso bamboo between 3 and 5years old at harvest (see Introduction for further details on processing). All three samples were prepared through grinding the material into a mix of sawdust and smaller particles. Each bamboo sample was analysed at a minimum in triplicate, and the mean values are given.

For the lignin and the carbohydrate content determination, samples were homogenised by grinding into a fine powder. The biomass composition process utilised 3g of each sample type, which were milled in a centrifugal grinding mill (Retsch ZM100) equipped with a 0.2mm sieve under liquid nitrogen environment. The carbohydrate identification and quantification were performed using HPAEC (ICS-5000+ DC, Dionex) following the procedure described elsewhere (Beaugrand et al. 2014). The neutral and acidic carbohydrates were determined from approximately 5mg of powdered bamboo samples, which were subjected to hydrolysis in 12M H2SO4 for 2h at room temperature, and then diluted with distilled water to 1.5M for 2h at 100C. Samples are then filtered and injected into a CarboPac PA-1 anion exchange column (4250mm, Dionex). The monosaccharide composition was quantified using 2-deoxy-d-ribose as the internal standard, and using standard solutions of uronic acids (d(+)-galacturonic acid and d(+)-glucuronic acid) and neutral carbohydrates (l-arabinose, l-fucose, d-glucose, d-xylose, d-galactose, and d-mannose). Analyses were performed in three independent assays. The carbohydrate content, the sum of the monosaccharide amounts, is expressed as the percentage of the dry matter mass.

Prior to Klason lignin quantification, 2.5g of each bamboo powder sample was subjected to a defatting step aimed at removing acid-insoluble extractives that may overestimate the Klason lignin amount. In the process, samples were subject to 6h extraction by soxlhet (500mL) with a laboratory grade (Sigma-Aldrich) ethanol-toluene (1/2 v/v) mixture in a chemical fume hood. The samples were then washed with ethanol (once) and then further with hot water (twice) and thereafter dried in an oven (Memmert, SingleDISPLAY 110) at 60C overnight. The lignin content was determined using the regular 72wt% sulfuric acid Klason method, as described in the Technical Association of the Pulp and Paper Industry (TAPPI) Standard method T 222 om-02 (TAPPI 2002), where the acid-insoluble residue is the non-hydrolysable acid residue remaining after sulfuric acid hydrolysis. For each bamboo sample, the ground and defatted samples (3 replicates for each condition, precisely 0.5g) were carefully immersed (to obtaingood wettability of the samples) in 3.0mL of 72% H2SO4 with a 20mL graduated glass pipette, in a 20mL beaker in fume hood and stirred every 15min with a glass rod for a total of 2h reaction at laboratory temperature (climatic lab 20C2). The beakers were capped and then the contents were carefully transferred into a 500mL Erlenmeyer flask and the beakers were meticulously rinsed with distilled water to avoid loss of particles, to a final volume of 115mL in the flask (approx. 3% H2SO4).

The flask was then equipped with a reflux condenser (16C target temperature) and the suspensions boiled for 3h with a hot plate (target temperature of 120C). The heating was turned off and the flasks were then let to cool down for 1h over the heating plate. Next, the acid insoluble lignin were collected in a pre-weighed (after drying at 105C overnight) filtering Gooch glass crucible where an extra filter were deposit (Whatman qualitative filter, mesh of 11m). The transferred acid-insoluble lignin was then rinsed in the crucible with warm distilled water (50C, filled in a 100mL measuring cylinder). The pH of the filtrate water was checked with a pH strip and was between 6 and 7 at the end of the rinsing; if it was acidic, more rinsing water was used. The remaining residues were dried at 105C for 20h, and thereafter cooled in a desiccator prior toweighing. The ash measurements were performed after an additional4h at 500C. The Klason lignin percentages were calculated using the differences in the mass of the samples before and after ash measurements.

Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) spectra were acquired (Perkin-Elmer, USA) with 16 scans taken for each sample with a resolution of 2cm1. A fine sawdust was scooped and packed onto the spectrometer. The spectral range was from 700 to 4000cm1. X-ray diffraction (XRD) analysis was carried out (Empyrean, PANalytical BV, Netherlands) at ambient temperature. A continuous scan was carried out for the angle range of 2=580 with data recorded every 0.2. Crystallinity (C) was calculated using Eq.1 (Park et al. 2010), where Itot is the intensity at the primary (002) peak for cellulose I (at 2=22) and Iam is the intensity from the amorphous portion evaluated as the minimum intensity (at 2=18.5) between the primary (002) peak and the secondary (101) peak (at 2=16).

High resolution 13C cross-polarisation (CP) magic angle spinning (MAS) solid- state NMR (13C CPMAS NMR) analysis was performed on a 400MHz spectrometer (Bruker Avance, USA) operating at 100.6MHz using a 4mm double resonance MAS probe spinning at 12.5kHz. The chemical shifts were measured relative to tetramethylsilane via glycine as an external secondary reference with the C set to 43.1ppm. Samples were packed in zirconia rotors, 4mm in diameter, with Kel-F cap. The experiments were carried out using a 50100% 1H ramped contact pulse with a contact time of 5000s and a proton power during contact of 3.5dB. The 13C power level during contact was 8.7dB. Spectra were collected for a total of 2048 scans. The recycle delay was 4s and experiments were carried out at ambient temperature.

Differential Scanning Calorimetry (DSC; TA Instrument, USA) was performed on as-produced bamboo powders (i.e. no prior drying) to examine the influence of treatment on degradation and glass transition behaviour. The measurements were made under nitrogen flow (100mL/min) from ambient to 600C with a constant heating rate of 10C per minute using an alumina crucible with a pinhole.

Dynamic Vapour Sorption (DVS) was used to obtain water adsorption isotherms (Hiden Isochema Ltd., UK). Water uptake was determined on small sticks of bamboo samples. The method used is described elsewhere (Placet et al. 2017) and was slightly modified as follows: the samples were first equilibrated at 95% relative humidity (RH), then a stepwise desorption setup was applied by decreasing the RH down to a dried state (0% RH), after which an adsorption cycle was performed. The cycle used approximately 5mg of bamboo samples placed into the stainless steel nacelle of the microbalance, which was then placed hermetically in the double jacket reactor that was connected to a thermostated water bath. The temperature was set to 20C. The water uptake of the bamboo fibre was recorded at each equilibrium of the chosen RH values, and calculated as the water uptake at each equilibrium moisture content expressed as the dry matter of the sample (at 0% RH).

The principal hemicellulose present in bamboo is 4-O-methyl-D-glucurono-arabino-xylan (Maekawa 1976; Vena et al. 2010). The xylan contains the residues d-xylose (Xyl) and l-arabinose (Ara), as well as small fractions of l-galactose (Gal) and Glucuronic acid (GalA) (Maekawa 1976). We observed that Xyl, which is usually more sensitive to chemical degradation than d-glucose (Glu), does not decrease with processing, but rather increases in proportion. This is the case for both the bleaching and caramelisation processes. The relative loss of Glu may reflect loss of betaglucan (mixed linkage glucan), because it is less likely that the crystalline cellulose isdestroyed by the procedures. The relative resistance to degradation of bamboo xylan may be related to its ability, like that of various xylans from other Poaceae (Beaugrand 2004; Beaugrand et al. 2004), to covalently bond with other xylan or lignins via hydroxycinnamic moieties (such as ferulic acids) to form a cross-linked network which limits chemical access. This behaviour would be similar to that of various xylans from the grass family (Beaugrand 2004; Beaugrand et al. 2004).

The degree of arabinose substitution (Xyl:Ara ratio) in bamboo differs from that observed in hardwoods and softwoods (Table2). Xyl:Ara ratios of 1520 have been previously reported for raw bamboo (Maekawa 1976; Shao et al. 2008). In comparison to bamboo, softwoods have relatively higher amounts of Ara (lower Xyl:Ara ratio), and hardwoods have fewer Ara residues (higher Xyl:Ara ratio) (Maekawa 1976; Timell 1973; Willfr et al. 2005). As shown in Table1, the processed materials indicate an increase in the Xyl:Ara ratio in comparison to the raw bamboo (18.7), with a slight increase in the bleached samples (21.0) and a marked increase in the caramelised material (29.1).

In comparison to wood materials, the increase in the Xyl:Glu ratio with processing is attributed to the different structure of bamboo. The degradation and solubilisation of d-glucose, likely belonging to mixed linked betaglucans or amorphous cellulose, and the resistance of bamboo xylan to degradation (Beaugrand 2004; Beaugrand et al. 2004), may explain the observation. Xyl:Glu ratios for hardwoods have been shown to vary from 0.13 to 0.55 (Huang et al. 2016). Bamboo xylan is also characterised by a rather high degree of acetylation. The acetyl group content represents 67% of total bamboo xylan, compared to the 817% acetyl group content in xylan of hardwoods and 49% in glucomannan of softwoods (Vena et al. 2010). An observed difference between the bleached and caramelised materials is the release of acetates during caramelisation, which is likely to be a result of degradation of the acetyl esters.

Bamboo lignin comprises p-coumaryl units with guaiacyl, syringyl and p-hydroxyphenyl moieties, similar to grasses, or Poaceae plant lignin (Banik et al. 2017). Although bamboo lignins are richer in phenolic hydroxyl groups than wood lignins, and therefore more reactive during pulping (Vena et al. 2010), no substantial change in Klason lignin content was observed upon bleaching the raw bamboo (Table1). This is likely because bamboo lignin is more resistant to bleaching than wood, as the former exhibits a higher degree of condensation (Salmela et al. 2008). In addition, our bamboos have been processed through lignin-preserving bleaching under much milder conditions than lignin-degrading bleaching (Ek et al. 2009). Consequently, while the bamboo bleaching process may lead to cell wall disruption and partial lignin oxidation (of chromophoric groups evidenced by the visual colour change), the lignin polymers are not solubilised or removed, but have been condensed and are still detectable.

The FTIR results are presented in Fig.2. The absolute averaged spectra are plotted for each material. The results indicate that there are only subtle differences between the two treated samples. The observed shifts in the bleached material compared to the raw Moso bamboo are attributed to the bleaching process oxidising the aromatic rings of the phenolic groups in the lignin (1230cm1), as well as the hydroxyl groups in the polysaccharides (1047cm1). The latter would result in shorter cellulose chains and reduced crystallinity (Ramos et al. 2008; Douek and Goring 1976; Kishimoto et al. 2003). The CO stretch at 1110cm1 has been attributed to loss of hydroxyl bonds and decomposition of hemicellulose (Zuo et al. 2003).

In comparison, the XRD spectra (Fig.3a) revealed no noticeable shifts in any of the cellulose peaks nor any changes in peak shapes; all spectra reveal a crystalline (101) peak at 2=16, a (002) peak at 12.5, and a (040) peak at 34.5. However, peak intensities differed in the treated materials. Analysis of crystallinity index (Fig.3b) reveals that while there is no statistically significant difference in the cellulose crystallinity of the raw and caramelised bamboos (p=0.8, 2-tailed t test), the bleached bamboo has a substantially reduced crystallinity in comparison to both the raw (p=0.10) and caramelised (p=0.0004) materials. The reduced crystallinity of bleached bamboo is supported by the ATR-FTIR analysis. Analysis of the diffractograms and comparison with reference spectra of Cellulose I and II from (Takahashi and Takenaka 1987), it is evident that a transition from cellulose I to cellulose II is not observed, although this may be expected in a typical bleaching or alkali-treatment process of cellulose (Liu et al. 2012). This supports the idea that a preserving bleaching process is used which eliminates the chromophoric groups in lignin, and while may lead to some depolymerisation, chain scission, and loss in crystallinity, is not harsh enough to substantially change the structure of cellulose from I to II.

XRD was used to determine the crystallinity of raw Moso, bleached and caramelised bamboos. a XRD diffractograms of the three materials. b Calculated crystallinity index presented in box plots, which indicate the mean, 1st and 3rd quartiles, with the range shown in the whiskers

Both bleached and caramelised bamboos undergo a steam-assisted drying step at 5060C at the end of their treatment; the bleached bamboo is dried for 72h, and caramelised bamboo for 240h. The duration of steam-assisted drying processes is known to influence crystallinity of cellulosic materials, such as Eucalyptus and Spruce woods (Kong et al. 2017; Bhuiyan et al. 2000), and presumably also bamboo. Kong et al. observe that saturated steam at 100C initially (up to 4h drying time) increases crystallinity of woods, due to moisture enabling higher mobility, reorientation and crystallisation of quasi-crystallised and amorphous regions. At higher drying times, increased chain scission reactions are proposed to increase amorphous fraction, and therefore reduce crystallinity. In our case, perhaps the lower drying temperatures (5060C, rather than 100C) in saturated steam, extend these effects over longer durations.

13C CPMAS NMR results indicate that for the bleached material signals in the 50110ppm region slightly decreased in intensity relative to the aromatics in the same sample when compared to the raw (Fig.4). Comparing the raw and caramelised bamboo indicates that the processing results in changes in the 140160 and 110120ppm regions of the spectra (highlighted in green). Peaks in this region are characteristic of aromatic or olefinic carbons, further analysis is required for full assignment.

In the DSC measurements (Fig.5), the large endothermic peak at 100C for all materials is attributed to the removal of water. All endothermic and exothermic peaks at temperatures above 150C for bleached bamboo occur at 1025C lower temperatures than that for raw and caramelised bamboo. The glass transition for the amorphous components is identified to be around 150175C based on the inflection point. During pyrolysis, hemicelluloses and lignins volatilise (which is endothermic) and cellulose chars and leaves substantial residues (which is exothermic) (Yang et al. 2007). The exothermic peaks between 325 and 375C are associated with hemicellulose and lignin pyrolysis, while the endothermic peak between 350 and 400C is attributed to cellulose pyrolysis (Yang et al. 2007). The shifts in peaks suggests changes in hemicellulose and cellulose during the chemical bleaching process, making them more prone to pyrolysis, including shortening of chains and reduction in crystallinity confirmed through XRD measurements. This is also consistent with the reduction in signal intensity in the 50110ppm region observed by NMR. The hygrothermally treated caramelised bamboo shows a fairly similar profile to raw bamboos, with very minor shifts.

Dynamic vapour adsorption plots illustrating moisture absorption and desorption isotherms for the three bamboo materials are presented in Fig.6. Typical type II sigmoidal profiles were observed, similar to that of plant fibres, depicting three distinct regions (Hill et al. 2009):

The hysteresis response can be explained by the differing conditions in which adsorption and desorption take place (Hill et al. 2009). During adsorption, the bamboo material deforms by swelling and the micro-capillaries expand. However, during desorption, relaxation to the previous state is kinetically hindered due to changes in internal free volume, pore space (or micro-capillary space), surface area and structure.

The dynamic vapour adsorption results suggest that at any given relative humidity, the moisture content is higher in the raw material in comparison to the bleached and particularly the caramelised materials. This indicates that processing reduces adsorption capacity, which is further observed in the final products with the raw, bleached and caramelised materials having an average equilibrium moisture content of 10, 8 and 6%, respectively. In addition, the processed materials also show a pronounced hysteretic response. For example, hysteresis for the raw bamboo peaks to 3.0 at 60% RH, but is as high as 3.9 and 3.5 at 70% RH for the caramelised and bleached materials, respectively. This is substantially higher than the 1.53% peak hysteresis typically recorded for plant fibres (Hill et al. 2009). In general, high amorphous polysaccharide content, particularly amorphous cellulose and hemicellulose, may be responsible for higher water accessibility and moisture uptake. Both processed materials have an insubstantially reduced glucose content (Table1), arguably belonging to cellulose (Maekawa 1976). Comparing the bleached and caramelised bamboo, we see greater effects on the caramelised products that are attributed to the removal of the hydroxyl groups, rather than the aromatics and phenolic groups in the bleached material.

In addition, differences in microstructure and micro-scale porosity also influence moisture capacity. The density of raw bamboo is lowest (at 562kg/m3), followed by bleached bamboo (644kg/m3) and caramelised bamboo (686kg/m3). This suggests that untreated bamboo would have the highest porosity content (Eq.2) at 62.5%, with the porosity content of bleached bamboo at 57.1% and of caramelised bamboo at 54.3%

The presented study investigated the effects of processing on the biochemical composition and chemical structure of raw Moso bamboo. The results indicate that the bleaching process results in a more pronounced degradation of the lignin in comparison to the caramelised bamboo. Subtle changes to the lignin composition and structure may have larger global effects in the form of fracture and crack propagation, however this is yet to be fully characterised. In general, caramelisation may have positive benefits for global material properties and durability of bamboo. This is further supported by previous experimental studies in which the bleached material often had a lower strength in comparison to the caramelised material. A better understanding of the effects of processing would help to elucidate the properties of bamboo and various derivative materials in structural applications.

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The authors thank Dr. Guanglu Wu and Dr. Li Yu for their support and contributions. JB thanks Miguel Pernes for his skillful assistance with the DVS experiment. This work was funded by a Leverhulme Trust Programme Grant, and EPSRC Grant EP/K023403/1. Data is available at the University of Cambridges Institutional Data Repository (https://doi.org/10.17863/CAM.22046).

Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

Sharma, B., Shah, D.U., Beaugrand, J. et al. Chemical composition of processed bamboo for structural applications. Cellulose 25, 32553266 (2018). https://doi.org/10.1007/s10570-018-1789-0

attrition scrubber

attrition scrubber

If clays are not liberated, the final frac sand product could fall outside required turbidity specifications. The general use of attrition scrubbers is to break down these clays, whether found in sand size particles or as coatings on the surface of sand grains, to allow for their rejection. Attrition scrubbing cannot change or alter the grain shape. If the particles arc not round, no economically justifiable amount of scrubbing will change that fact.

Attrition scrubbers drives can either be gearbox driven, or via belts and sheaves. Gearbox driven units tend to be higher in capital costs, but offer long-term operation without any sacrifice in performance. Belt drives tend to be less expensive, but as the belts and sheaves wear, they need to be replaced, adding to maintenance cost and down time Often, operators w ill add water to prevent plugging of the attrition cells rather than replacing the worn parts. The lower percent solids created by this added water prevents attrition scrubbers from operating as designed so product quality is ultimately sacrificed.

Attrition scrubbing is the process where a mineral is scrubbed primarily by theaction of the slurry particles impactingone another. This type of particle scrubbingachieves the desired cleaned particles while minimizing wear on the Attrition Cells.

Our attrition scrubbers range in size from 1 to 3 cubic foot cells, with up to four cells per bank. This size range is particularly suitable for pilot plant projects, environmental remediation projects and small production operations.

The attrition scrubbers have two opposed axial flow propellers (100% and 150% pitch) to create a high intensity impact zone between these propellers. Each particle is violently impacted with many other particle surfaces many times before discharge from the vessel.

Single cell attrition scrubbers may be operated as batch units. Multiple cell attrition scrubber units are designed to create a continuous flow through the bank of cells. The discharge from the first cell is forced down and under the propellers of the second cell, where the flow is upward and is discharged to the top of the third cell. This alternating flow pattern assures an even conditioning and efficient flow pattern throughout a multiple cell scrubber unit.

The Attrition Scrubber provides a simple, economical solution to many of todays beneficiation problems. Many products can be made marketable by the removal of surface films, coatings or slimes. An important example is the glass sand industry where removal of iron stains and slimes results in a premium product. Certain applications require the disintegration of clay balls or bituminous matter. In many cases important mineral values occur as slime coatings on sand grains or as cementing materials. Attrition Scrubbers remove these coatings, thus upgrading the mineral values. Other applications include high density reagent conditioning for better flotation such as is required in the treatment of phosphate and certain other non-metallic ores.

The scrubbing action must be carried out at high density (between 70% and 80% solids by weight) which results in grain-to-grain attrition within the mass. This intense scrubbing action requires high horsepower consumption.

The Attrition Scrubber was developed to impart this horsepower with the highest degree of efficiency. The high efficiency is achieved with the rubber-covered Turbine Type Propellers which are designed to move a large volume of dense material through the propeller zone with a minimum horsepower input. And, of equal importance, is the fact that the design of the turbines minimizes abrasive wear and cavitation.

Each cell assembly has two turbines of opposite pitch. The particles impinge on each other in the zone between the turbines. The turbines, in addition to being of opposite pitch also have a different degree of pitch which imparts a shearing action, thus keeping the entire cell volume action.

Sizes range from the 11 x 11 tank to the 56 x 56 tank. Attrition Scrubbers are available in 2-cell, 4-cell and 6-cell units. On cells of 48 x 48 and 56 x 56 enclosed reducer drives are supplied. Turbine assemblies and tanks are available with rubber, neoprene or abrasion-resistant steel liners as required for the application.

An attrition scrubber, patterned after the U. S. Bureau of Mines model, was built at the M.I.T. Mineral Engineering Laboratory and tested in the scrubbing of western carnotite and roscoelite ores. Tests indicated that the sand product increased in purity as the amount of work put into the scrubbing increased. The time of scrubbing was of maximum importance. Speed, pulp density and size of charge had progressively less effect on the purity of the sand product.

The object of attrition scrubbing is to produce clean grain surfaces by the removal of surface stains or cements without appreciably reducing the size of the discrete grains. In some cases the cleaned grains are the valuable product, as in glass sands, or where a selective flotation or electrostatic separation is to be made, as in the case of spodumene and chromite, but in others the stain or cement is the valuable constituent, as exemplified by carnotite and roscoelite ores.

A number of machines may be used to accomplish the scrubbing, among which are grinding mills, both with and without a grinding medium, flotation machines, paddle, screw or rake washers, and especially constructed agitators or attrition scrubbers.

The attrition scrubber, a relatively new tool in the field of mineral dressing, is a laboratory machine that was invented by Mr. James Norman and developed at the Eastern Experiment Station of the Bureau of Mines. Its function is properly described by the word scrub, which means to rub something hard, or to cleanse by rubbing, and the redundant name was conferred on it to emphasize the intensity of its rubbing action. The motor that drives the attrition scrubber is larger than the container for its charge. The attrition scrubber has had limited application up to now, but some installations of scrubbers of this type have been made on a commercial scale. The history of the development of the attrition scrubber, including a bibliography, was given in a letter from Mr. John Dasher to Mr. J. K. Gustafson dated April 5, 1948, a copy of which forms appendix G of this report.

An attrition scrubber, patterned after the Bureau of Mines model was constructed at the M.I.T. Mineral Engineering Laboratory and tested in the scrubbing of four western carnotite and two western roscoelite ores. The origins of these ores, together with comparative analyses, are given in Topical Report MITG-207 dated September 30, 1918, but for purposes of ready reference Table 1 below duplicates some of this information.

An attrition scrubber was built and tested in the scrubbing of four Western carnotite and two Western roscoelite ores. The tests showed that the sand product increased in purity as the amount of work put into the scrubbing increased, the time of scrubbing being of maximum importance. Speed, pulp density and size of charge had progressively less effect on the purity of the sand product.

Metallurgically, there is small choice between the quality of work done by the attrition scrubber and some other methods of scrubbing, such as treatment in a flotation machine or attrition with steel punchings in a mill, so the choice of scrubbing procedure for any particular ore will depend chiefly on economic considerations, that is the value of the product less the cost of the power required and the cost of subsequent treatment per ton. Since work with the carnotite and roscoelite ores was terminated before power requirements for the different scrubbing procedures could be determined, this question is still unresolved.

The Fall Creek roscoelite ore and the Gypsum Valley carnotite ore gave the best response to scrubbing, while the Rico roscoelite ore and the Mexican Hat carriotite ore were the most difficult to scrub.

More extensive testing of all the ores was outlined. It was planned to determine the power requirements for each of the different scrubbing procedures, to make additional tests at longer intervals of self-attrition, and at shorter intervals of scrubbing with steel punchings, so that more comparative results might be obtained. Also an investigation of other scrubbing media, such as rubber balls or rubber covered steel rods should still be made.

The attrition scrubber constructed at the M.I.T. Engineering Laboratory is an agitator, with a rotor and a stator which almost fill the space where the pulp is confined. The space between the rotor and stator is small, but it is several times the diameter of the largest grain to be scrubbed, so that no grinding takes place, but a severity of agitation sufficient to rub off the coating on mineral grains without breaking the grains is attained.

The stator is made from a section of five inch steel pipe, nine inches long, welded to a square steel plate. The pipe is lined with 0.25 inch of Haveg, a laminated phenol-formaldehyde plastic, and three sets of blades, four in each set, 0.5 inch x 1.5 inches x 0.125 inch are attached to the inside of the pipe with threaded pins. Each blade in a set is placed at an angle of 90 or 180 degrees with the other blades in that set and the blades are covered with rubber.

The rotor consists of a shaft, 0.5 inch in diameter, to which three sets of blades, four in each set, similar to those in the stator but 0.25 inch longer, are welded cruciformly. The blades are two inches apart and are so placed that when the shaft is rotated, and the stator is in place, they pass between the stator blades. The rotor blades are also covered with rubber.

The rotor is mounted on a steel framework, which carries the Doall Speedmaster (Model 4B) used to change or control the rotor speed, and the electric motor to drive the rotor. A 0.5 hp, 1725 rpm, single phase electric motor is used.

For the self-attrition tests an assay-size porcelain mill running at 72 rpm was used, and for the tests where steel punchings provided the scrubbing medium, a slowly rotating (6 rpm) cast iron mill, 8 in diameter x 7 long, charged with 4 kilos of 0.5 inch x 0.125 inch steel punchings, was employed. The cast iron mill was turned by placing it on two rotating steel rolls.

A standard laboratory model Fagergren flotation machine having an impeller speed of 1775 rpm was used for the scrubbing tests at 20 per cent solids, and this same impeller and housing, stripped of its wings, was used for some of the tests at 50 per cent solids by lowering the mechanism into a 1500 ml beaker containing the pulp. The beaker rested or a rubber mat to prevent rotation.

For the purpose of comparing different methods of operating the attrition scrubber, certain arbitrary conditions were selected and designated as standard, operating conditions. These conditions were based on published data obtained in the operation of a similar attrition scrubber and appeared to be a satisfactory starting point for testing the MIT machine.

Standard speed was selected as the speed obtained in operating the scrubber when one-quarter horsepower of energy was being expended on 500 grams of charge at 50 per cent solids. It was determined by running the scrubber empty, to obtain a measure of the power consumed by the motor, bearings, pulleys and belts, then adding the pulp and adjusting the scrubber speed until the ammeter showed that one-quarter horsepower was being impressed, in addition to the power required by the empty scrubber a power factor of 85 per cent was assumed for the small fractional horsepower motor used.

Five hundred grams of ore was also the standard charge for the Fagergren flotation mechanism tests, with 20 per cent solids standard for the regular flotation cell tests and 50 per cent solids for the beaker tests. Standard time of scrubbing for all of these tests was 20 minutes.

Fractionation of the scrubbed pulps from all tests was carried out in the following manner. Four pounds of Daxad 23 was added per ton of ore, usually to the pulp during scrubbing, to insure thorough dispersion. The scrubbed pulp was transferred to an eight liter jar, 23.5 cm in diameter and 23.5 cm deep, and distilled water added until the pulp depth became 13 cm. This gave a pulp dilution of 10 per cent solids for the tests with 500 gram ore charges, 14.3 per cent solids for the tests with 750 gram ore charges and 18.2 per cent solids for the tests with 1000 gram ore charges. The pulp was then vigorously stirred and allowed to settle for 16 minutes, at the end of which time the suspended solids were removed by a special glass siphon with a turned-up tip on the short end. The depth of pulp removed was 11.5 cm out of the total depth of 13 cm. The volume was next made up to the original point with distilled water, the pulp agitated, allowed to settle for 16 minutes and a second fraction of suspended solids removed as before. Both 16 minute fractions were combined and treated as a single fraction.

Four fractions were made in each test rather than the two required, because, at the time the tests were run, it was not possible to get rapid assays of the test products, and consequently it could not be determined whether the split should be made after sedementation for one minute, two minutes, four minutes or some other time.

The influence of four variables on the quality of work done by the attrition scrubber was investigated by tests on two different ores. One a carnotite, that was relatively easy to scrub, as shown by self-attrition tests in a porcelain mill without scrubbing medium, and the other a roscoelite, that similar tests showed was difficult to scrub. Tests were run on each of these ores wherein the time of scrubbing, the pulp density, the speed of scrubbing and the size of the charge were varied one at a time.

The effect of varying the time of scrubbing is shown in Table 3. The results indicate that as the time of scrubbing increases, and more work is done on the ores, the weight per cent of the sands fraction decreases, as well as the content of both uranium and vanadium in the sands fraction.

The carnotite ore showed the best response to scrubbing. Doubling the time of scrubbing this ore resulted in a lowering of both the uranium and vanadium content of the sands by about 10 per cent each time it was doubled.

The roscoelite ore was more refractory. Doubling the time of scrubbing resulted in only about 4 to 6 per cent reduction in the uranium and vanadium content of the sands of this ore each time, and a twenty-fold increase in scrubbing time still left better than 38 per cent of the total uranium in the sands.

Progressive increases in the pulp density of the carnotite ore resulted in a corresponding increase in the uranium content of the sands fraction, although almost no change in the weight per cent of the sands was shown. The vanadium acted in about the same way as the uranium.

The roscoelite ore, however, showed a decrease of about 10 per cent in both the uranium and vanadium content of the sands fraction as the pulp density was increased from 50 per cent solids to 70 per cent solids. A small decrease, about 3 per cent, was also obtained in the weight per cent of the sands.

It should be pointed out that the calculated horsepower-hours per ton shown for some of the tests is probably high because of a mistaken belief that the attrition scrubber had been properly worked-in at the time the blank measurement of the amount of power consumed by the scrubber itself was made, and that there would be no appreciable change in this amount during the short time the tests were being made. After completion of the scrubbing tests some anomalous results prompted a check of the blank, and it was found that a considerable reduction in power consumption had taken place. The scrubber drew 9 amperes at first, but only 7.5 amperes at the end of the tests, so the horsepower calculations were made on the basis of this last figure and are, without doubt, unduly high in some instances. The effect of the blank reading is large, for the standard ampere increase due to the pulp is only 2 amperes, and the 1.5 amperes difference in the blanks means that the 20 hp-hrs/T intended as work input may actually have been 35 hp-hrs/T.

Operation of the scrubber at 80 per cent of the standard speed resulted in lowering the work input by about 50 per cent, in scrubbing both the carnotite and roscoelite ores, but about 10 per cent more uranium was left in the sands fraction of the carnotite ore, and 6 per cent more in the sands fraction of the roscoelite ore by this action.

Increasing the speed to 120 per cent of the standard resulted in an increase of work input with both ores, but the increase was not uniform, being greater with the roscoelite ore than with the carnotite ore.

An optimum speed at which the scrubber should be operated is indicated by the tests, especially those with the softer carnotite ore, where higher speed not only resulted in an increase in work input but also in the amount of uranium contained in the sands fraction. The optimum scrubber speed for the roscoelite ore was evidently not attained, because progressively higher speeds showed less and less uranium in the sands fraction.

The results show that, aside from efficiency of operation, the size of the charge to the attrition scrubber has little effect on the quality of work done by the scrubber. For maximum efficiency, therefore, the scrubber should be operated at its full capacity.

Both the carnotite and roscoelite ores were tested by methods of scrubbing other than with the attrition scrubber. These methods comprised self-attrition in a rotating porcelain jar for 2, 4 and 6 hours, scrubbing in an iron mill with steel punchings for 2, 4 and 6 hours, agitation in a Fagergren flotation machine at 20 per cent solids for 20 minutes and agitation in a beaker at 50 per cent solids with a Fagergren machine mechanism, minus its wings, for 20 minutes.

The six graphs, Figures 1-6, which follow show the results obtained with these different scrubbing procedures as compared with scrubbing in the attrition scrubber under standard conditions, each individual ore being represented by a single graph. The data from which these graphs were drawn may be found in Appendixes A to F, inclusive.

The graphs were constructed by plotting the per cent of U3O8 in the sands against the weight per cent of the sands, with 100 weight per cent and zero per cent U3O8 at the extreme right. It follows, then, that the lower down on the graph and the further to the right that a point appears, the better the result it represents.

Keeping this fact in mind it appears that the work of the attrition scrubber was outstanding only with the Gypsum Valley carnotite ore (sample D3). With the other ores there is little choice between the results obtained with the attrition scrubber and with those obtained by other methods of scrubbing, excepting that the self-attrition tests gave consistently poorer results than those of any other scrubbing method.

The problem of choosing the best method of scrubbing resolves itself therefore, into one of economics. Is it more economical to scrub three minutes in the attrition scrubber than twenty minutes in the Fagergren cell or 2 to 6 hours in a mill with steel punchings? Tests were contemplated where the power consumed in these different scrubbing procedures would be measured, but the work was discontinued before they could be made, so the question is still unresolved. Other tests were also contemplated to get more comparable results, specifically, tests of self-attrition at longer time intervals and of scrubbing with steel punchings at shorter time intervals. Also tests of other scrubbing media, such as rubber balls or rubber covered rods, were planned.

high-mobility p-type semiconducting two-dimensional -teo2 | nature electronics

high-mobility p-type semiconducting two-dimensional -teo2 | nature electronics

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Wide-bandgap oxide semiconductors are essential for the development of high-speed and energy-efficient transparent electronics. However, while many high-mobility n-type oxide semiconductors are known, wide-bandgap p-type oxides have carrier mobilities that are one to two orders of magnitude lower due to strong carrier localization near their valence band edge. Here, we report the growth of bilayer beta tellurium dioxide (-TeO2), which has recently been proposed theoretically as a high-mobility p-type semiconductor, through the surface oxidation of a eutectic mixture of tellurium and selenium. The isolated -TeO2 nanosheets are transparent and have a direct bandgap of 3.7eV. Field-effect transistors based on the nanosheets exhibit p-type switching with an on/off ratio exceeding 106 and a field-effect hole mobility of up to 232cm2V1s1 at room temperature. A low effective mass of 0.51 was observed for holes, and the carrier mobility reached 6,000cm2V1s1 on cooling to 50C.

Laun, J., Vilela Oliveira, D. & Bredow, T. Consistent Gaussian basis sets of double- and triple-zeta valence with polarization quality of the fifth period for solid-state calculations. J. Comput. Chem. 39, 12851290 (2018).

Mirgorodsky, A. P., Merle-Mjean, T., Champarnaud, J. C., Thomas, P. & Frit, B. Dynamics and structure of TeO2 polymorphs: model treatment of paratellurite and tellurite; Raman scattering evidence for new - and -phases. J. Phys. Chem. Solids 61, 501509 (2000).

Di Nardo, S., Lozzi, L., Passacantando, M., Picozzi, P. & Santucci, S. Reactivity towards oxygen of TeSi(100) surfaces investigated by ultraviolet photoelectron spectroscopy, X-ray photoelectron spectroscopy and low energy electron diffraction spectroscopy. J. Electron Spectrosc. 74, 129134 (1995).

T.D. acknowledges funds received from the Australian Research Council (ARC) through the DECRA scheme (DE190100100). A.Z. thanks the University of Melbourne for the support received through the McKenzie postdoctoral fellowship programme. This work was supported by ARC Centre of Excellence FLEET (CE170100039) and Exciton Science (CE170100026). We thank RMIT Universitys Microscopy and Microanalysis Facility (RMMF), a linked laboratory of the Australian Microscopy and Microanalysis Research Facility (AMMRF), and RMIT Universitys MicroNano Research Facility (MNRF) for scientific and technical support. The Cypher ES AFM instrument was funded in part by grant no. LE170100096 from the ARC. This project was also supported by computational resources provided by the Australian government through the National Computational Infrastructure National Facility (NCI-NF) and the Pawsey Supercomputer Centre (ARC). A.E. is supported by the Jack Brockhoff Foundation (JBF grant no. 4655-2019-AE). D.L.C. is supported by the ARC under Discovery Project grant no. DP190102852.

The project was designed and directed by T.D., C.F.M. and A.Z. A.Z. and P.A. synthesized the chalcogen mixture and developed the synthesis procedure for 2D -TeO2 while also conducting XPS and Raman measurements. A.Z., P.A. and B.Y.Z. performed the AFM imaging. A.E. performed atomic-resolution HR-AFM imaging. A.Z. performed TEM/SAED and HRTEM imaging. P.A. led the device fabrication with contributions from H.T., N.S., A.J., K.A.M. and J.v.E. J.G.P., A.Z. and P.A. characterized the FET devices. B.J.M. carried out UPS measurements and assisted with the XPS analysis. M.W. performed 2D nanosheet transfer experiments. D.L.C. conducted and interpreted Hall effect measurements. S.P.R. performed DFT calculations. T.D., C.F.M., K.K.-Z., A.Z. and P.A. analysed the material and device characteristics and drafted the manuscript. All authors revised the manuscript.

a, Maximum droplet velocity achieved when droplet size was varied (Supplementary Videos 1 and 2). Lower speeds can be applied to the larger droplets as rolling too fast causes the fragmentation. b, Oxide thickness against time shows no significant change of the sheet thickness when prolonging the oxidation time. c, Rolling time-steps against substrate coverage and sheets lateral dimensions (Supplementary Video 3). Time-steps are defined as resting molten droplet before rolling a droplet-diameter length. Each error bar represents 1 standard deviation from four measurements. Discussion on printing parameters can be found in Supplementary Note 1.

The results reveal the composition of the 2D sheets, shown in Fig. 1a (97.7mol% TeO2 and 2.3mol% Se). a, The peak in the O 1s binding energy region located at 530.6eV is associated with TeO242 b, The Te4+ 3d5/2 peak is located at 576.4eV42. c, A small amount of Se was detected in the Se 3d region with a peak located for the 3d5/2 at 55.2eV43. d, XPS elemental map of a deposited flake on the right indicates the TeO2 flake, while Se is revealed as a sparse residue on the substrate.

a-i, Transferred 2D TeO2 sheets on a variety of substrates. The labels I-IX refer to the different substrates, while X represents the 2D TeO2 sheet. j, A thicker TeO2 sheet can be obtained from repeated roll transfer across the same area. The optical image and AFM step height profile reveal multiple TeO2 sheets stacked on top of one another, which caused an increase in thickness. k-m, Transfer of a TeO2 flake from a GaAs substrate onto a SiO2 substrate. Optical images of the TeO2 flake on GaAs, polypropylene-carbonate (PPC) and SiO2 substrate, respectively, demonstrate the successful transfer process (See Methods section for the transfer protocol). Black scale bars are 50m.

The results show which types of atomic orbitals of Te and O contribute to the upper valence bands. The projections are partitioned into the different atomic orbital types (s, p, d) for O and Te. The plot clearly shows that in the region near the valence band maximum, O and Te p orbitals form the major contribution to the bands, suggesting -bonding.

For simplicity, the crystal structure of the bottom layer of the two layers found in unit cell thick -TeO2 (Fig. 1c) is shown. The charge density shown in Fig. 1c suggests that conduction most efficiently occurs close to the interlayer band edge (top side of the displayed monolayer), while the DOS associated with the VBM is sparse at the bottom of the shown -TeO2 layer. Here the conduction pathways are shown along the b-axis (green) and the a-axis (red). The DFT calculations indicate a hole mobility of 7690cm2 V-1 s-1 along the b-axis and 436cm2 V-1 s-1 along the a-axis, respectively. The higher mobility along the b-axis arises due to the shorter mean free path lengths and transport through regions of high DOS, while transport along the a-axis requires a longer mean free path that diverts into regions of low DOS.

Zavabeti, A., Aukarasereenont, P., Tuohey, H. et al. High-mobility p-type semiconducting two-dimensional -TeO2. Nat Electron 4, 277283 (2021). https://doi.org/10.1038/s41928-021-00561-5



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wind chimes, chimes, windchimes, wind chime, suncatcher

wind chimes, chimes, windchimes, wind chime, suncatcher

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top 20 ferrous scrap processors in the united states - recycling today

top 20 ferrous scrap processors in the united states - recycling today

A list of the nations largest ferrous scrap processors paints an interesting portrait. They are headquartered throughout the U.S.on all coasts and throughout the interior of the country. Many large scrap companies have an unmistakable leadership position in the regional markets they serve, while the largest ones are striving to achieve that position in several regions at once.

But while there are common denominators to the 20 largest ferrous scrap companies in the U.S., there are also differences. Some are publicly traded, while many are privately or closely held. One of the largest is owned by an overseas holding company.

The statistical snapshots we have assembled about these companies can be seen on the chart on pages 40 and 42. What we are also doing on the following pages is presenting thumbnail sketches of who these companies are and how they got to be among the biggest (and presumably best) in their industry.

A list like this can provoke debate. Unfortunately, a reluctance by some companies to provide information may have led to their omission from the list. We suspect this is just fine with the companies in question.

However, we hope that some of these companies will reconsider. Listing the largest, most active companies is a way to gain recognition for what a company and its employees have accomplished. It takes hard work by a lot of people to procure, process and ship out ferrous scrap.

Business owners who have grown or nurtured a business so that it has become among the leaders in its industry should be justifiably proud. We hope that our recognition of those companies in the ferrous scrap segment that have accomplished this feat will be seen for what it is: A way to honor leadership in an industry that can provide challenges with each price adjustment and each twist and turn of the market.

The Chicago area operations of Cozzi Iron & Metal make up a key part of Metal Managements current assets, but during its formation in 1997 and 1998, the company also acquired several regional companies, including: several smaller operators in the Chicago area; Perlco in Memphis, Tenn., and Salt River Recycling in Phoenix, which Cozzi had previously acquired; Naporano Iron & Metal Co., Newark, N.J.; Michael Schiavone & Sons, North Haven, Conn.; Proler Southwest, Houston; Newell Recycling of Denver Inc.; Emco Recycling Corp., Phoenix; Ellis Metals Inc., Tucson, Ariz.; The Isaac Group, Toledo, Ohio; M. Kimmerling & Sons, Birmingham, Ala.; Charles Bluestone Co., Elizabeth, Pa.; Nicroloy Co., Pittsburgh; and Aerospace Metals, Hartford, Conn.

The companys 1,600+ employees buy, process and sell more than $750 million worth of metals annually, working from locations in 14 different states. In addition to its ferrous operations, the company also trades heavily in nonferrous metals.

The publicly released results of Metal Management reflect the difficulties faced by scrap recyclers in 2001. For its quarter ending Sept. 30, 2001, Metal Managements revenues were down more than 20% compared to the same period last year, reflecting a much slower flow of materials through its yards.

The good news, says Cozzi, is that the company has reigned in its operating and administrative expenses, and a significant improvement in financial results can be anticipated when market conditions improve.

With its headquarters in Fort Wayne, Ind., and its roots lying there and in nearby Toledo, Ohio, OmniSource Corp. was born with the combination of two family businesses located in each of those cities.

In Fort Wayne, the Rifkin family built Superior Iron & Metal into a formidable regional company, while the Tuschman family did the same with Kripke-Tuschman Industries in Toledo. When the two companies merged in the 1980s, the Rifkins assumed overall operating control (though the Tuschmans remain involved in Toledo), and the name OmniSource was chosen for the company.

Although OmniSource grew significantly during the 1990s, it did not go on an acquisition spree as much as it acquired additional facilities in or adjacent to the regional market with which it was familiar. The company branched into Michigan in addition to acquiring more locations in Indiana and Ohio. It also began important service contracts at major automotive plants that provided it with access to steady supplies of scrap.

Four Rifkin family members are currently officers with the firm. CEO Leonard Rifkin told Recycling Today in 2000 that the family members have always been "committed to the building of the business, rather than the concept of trying to take the money out of the business. We wanted to build something for our families that could some day be considered one of the top companies in the U.S."

Several other companies are processing tonnage that puts them near the Top 20. Among those companies poised to reach the top 20 are Newell of Atlanta; General Iron Industries, Chicago; American Compressed Steel, Kansas City, Mo.; Morris Recycling Inc., Albany, Miss.; and Atlantic Scrap and Processing LLC, Kernersville, N.C.

Several other companies that were contacted were not able to provide information, and we were not able to make contact with sources who could provide reasonable estimates. Those companies include Sadoff Iron & Metal Co., Fond du Loc, Wisc.; Yaffe Cos. Inc., Muskogee, Okla.; Louis Padnos Iron & Metal Co., Holland, Mich.; Adams Steel, Anaheim, Calif.; Pacific Coast Recycling, Long Beach, Calif.; Azcon Corp., Chicago; and Tennessee Valley Recycling, Decatur, Ala.

Founded in 1926 by Lithuanian immigrant David Coslov, Tube City has grown to become an international ferrous scrap processor handling more than seven million tons annually. The company remains under management of members of the Coslov family.

While the name Tube City Iron & Metal was chosen to reflect its location, just two years later the company moved to Glassport, Pa., where it is still headquartered. In 1987, when the company was acquired by Davids grandson, I Michael Coslov, the name of the firm was shortened to Tube City Inc.

Tube City sites many of its yards to take advantage of strategic partnerships with steel mills such as U.S. Steels Gary, Ind., complex; the Great Lakes Steel mill near Detroit; the U.S. Steels Fairless Hills complex in Pennsylvania; and the Co-Steel mill in Sayreville, N.J.

The company cites as its mission to "provide quality products and services to satisfy steel industry needs. We are committed to excellence and industry leadership through innovation, quality and a close partnership with our customers."

Like Metal Management, Philip Metals Inc. arose from the consolidation wave that swept the scrap industry in the 1990s. Cleveland-based Philip Metals is part of Philip Services Corp. (PSC), which has offices in Chicago and Hamilton, Ontario, Canada.

The companys scrap roots trace to both Hamilton, where companies like Intermetco and Waxman Industries were early acquisitions for PSC, and to Cleveland, long-time home of Luria Brothers Inc., one of the largest acquisitions made by PSC.

Similar to fellow consolidator Metal Management, Philip has been through bankruptcy proceedings and is trying to emerge from the current depressed scrap markets as a coast-to-coast scrap recycling services provider. Also like Metal Management, the companies acquired by PSC include some prominent scrap recycling names. In addition to Intermetco, Waxman and Luria Brothers, these firms include: Steiner-Liff Metals, Nashville, Tenn.; Southern Foundry Supply, Chattanooga, Tenn.; and Luntz Corp., Canton, Ohio.

At least twice during the past three years, PSC has explored selling its metals recycling assets. Currently, its nine auto shredders and other considerable operations place it among the largest scrap processors in North America.

Headquartered in Manhattan, the operations of Hugo Neu Corp. reflect the cosmopolitan nature of that global business center. The company is probably Americas single largest exporter and importer of scrap materials

In 1945, at the close of World War II, Neu started his own company, buying and selling primary and scrap metals, as well as machinery, ores and residue. The company grew along with the booming post-World War II economy, and was particularly adept at following up on international trading opportunities.

The companys global operations caused them to also expand beyond New York in the U.S., with Hugo Neu establishing offices or operations in states ranging from California and Hawaii to New Jersey and Florida.

Strategic partnerships have also been a part of Neus past and present. Partnerships with the Prolers in Houston expanded Hugo Neus presence in the West and South. A current partnership with Schnitzer Steel Industries Inc., Portland, Ore., has helped maintain the Neu presence in the West.

The Motor City is a major generator and consumer of ferrous scrap, and Ferrous Processing & Trading Co. (FPT) went on a major growth spurt in the 1990s in order to dominate the ferrous scrap trade in this important regional market.

FPT is owned by Soave Enterprises, based in Detroit and run by Anthony Soave, who initially built his holdings with the solid waste firm City Management Corp., which he eventually sold to a national solid waste company.

Guided at first by former CEO Jeffrey Cole, and now by current president Howard Sherman, FPT operates three shredding plants in and around Detroit. The company acquired many of its area competitors, including nonferrous recycling company SLC Recycling in Warren, Mich., and Zalev Brothers Co., of Windsor, Ontario, Canada.

The company has made metals shredding the core of its business, including the operation of a capital-intensive downstream system at the SLC facility, where premium nonferrous grades are harvested from the post-shredder stream.

The Dallas-based company operates facilities in several southern states, with both considerable ferrous and nonferrous scrap operations. The company traces its origins back to 1915, with a single scrap yard opened in Dallas by Moses Feldman. Moses son Jake guided the company through strong regional growth in the 1940s and 1950s. In the 1950s CMC became one of the first scrap firms in the U.S. to offer publicly-traded stock.

Although it is publicly traded, CMC did not engage in massive acquisitions in the mid and late 1990s. The company has also not suffered from the same red ink-drenched balance sheets as some of its other publicly-traded competitors. "Basically, we did it more systematically," CMC Secondary Metals Processing Division president Harry H. Heinkele told Recycling Today in 1999. "We had no mandate to try to double, triple or quadruple overnight. This allowed us to integrate new operations as we acquired them."

The company added other metals-related operations to its company activities. By 1914, the scrap operations were managed by Josephs youngest son David, and included locations in seven cities. When World War I demand for scrap iron boomed, Joseph Joseph Brothers and Company was poised as a leading supplier of the material.

After the war, in 1921, David Joseph established the scrap division as the David J. Joseph Co. (DJJ). The company boomed during the 1920s and staggered through the Great Depression years. Following World War II, David J. Joseph Jr. became president of the company.

Under his leadership, the company prospered throughout the 1950s, 60s and 70s. In 1975, the company was purchased by the Dutch holding company SHV Holdings. While the holding company has retained ownership throughout the years, it has largely allowed the Cincinnati-based management team to operate DJJ as its sees fitand has not regretted doing so.

The company bills itself as "a full-service supplier of value-added ferrous raw material sourcing strategies; a multi-faceted corporation with a global presence, generating over $1.5 billion in sales each year."

Offering recycling and transportation services, plus international brokering of scrap and scrap substitutes, DJJ has trading offices and plants in 20 states plus Mexico, and employs nearly 1,200 people. The company is also involved in additional joint ventures.

Schnitzers Cascade Rolling Mills division makes steel rod, wire and rebar. The companys scrap business focuses on ferrous materials. The scrap operations include joint ventures with Hugo Neu Corp. of New York.

Large shredder yards in Pacific Coast cities of Portland, Oakland and Tacoma, Wash., are key outposts in Schnitzers scrap empire. The export facilities ship to steel mills in Asian markets such as South Korea, China, Japan, Taiwan and India.

Leonard Schnitzer told Recycling Today for an article written nearly ten years ago that he is proud of the companys role as a true recycler. We start with [obsolete] automobiles at one end of the pipeline, and steel rebar, flat bar and structural steel comes out of the other.

Pittsburgh-based AMG Resources traces its origins back to some detinning operations that got their start in the early 1900s. But the company really got rolling after 1988, when current president Allan Goldstein purchased detinning plants in the U.S. and the United Kingdom, and prepared to acquire additional operations to boost the newly acquired business growth potential.

Subsequently, AMG has acquired operations in New Jersey, Missouri, Wisconsin, Iowa, California, and started greenfield scrap recycling facilities in Minnesota and Puerto Rico. AMG Resources has also focused on scrap brokerage, and now operates 12 brokerage offices in addition to its 11 processing facilities.

The industrial state of Wisconsin provides plenty of generated ferrous scrap for Miller Compressing Co., Milwaukee. The companys six scrap facilities house two auto shredders, with some having access to Great Lakes shipping routes.

Simsmetal established its foothold in North America with the 1988 purchase of LMC Metals Co. (Levin Metals Co.), a San Francisco Bay Area scrap company around which Sims has built its North American operations.

The bustling Gulf Coast region is home to Southern Scrap Recycling, New Orleans. Auto shredders help process the ferrous scrap flowing through Southerns Gulf Coast area yards, while access to shipping routes along the coast and the industrial canal that serves New Orleans provide shipping options.

Although headquartered in St. Louis, the bulk of Alters scrap operations are located to the north in Iowa. The company is a prominent barge shipper of ferrous scrap, using the inland waterways to reach EAF mills in Arkansas and other states.

TXI Chaparral, Midlothian, Texas, operates a large ferrous scrap yard to produce feedstock for its EAF steel mill. The company has built a second mill in Virginia, and is expected to soon ramp up recycling operations at an adjacent scrap yard.

The North Star Steel division of Cargill Inc., Minneapolis, meets some of its feedstock needs with ferrous scrap prepared by North Star Recycling. Last year, North Star Recycling provided 400,000 tons of the approximately three million tons of EAF feedstock required by North Star.

Operating shredders in its home market of Kansas City, Mo., Galamet Inc. has grown into a formidable regional competitor. Members of the Galemba family help oversee operations at the companys primary location in Kansas City as well as several feeder yards.

Processing the industrial and obsolete scrap of southern New Jersey is the job of Camden Iron & Metal. The firms two shredder yards and two additional locations prepare scrap for domestic and export shipments.

Long Island, New York serves as the home of Gershow Recycling, a family business with five facilities, four shredding plants (including a recently acquired one in Brooklyn that is being rebuilt) and access to a deepwater shipping port.

Local and state governments, OEMs, commercial businesses and others can utilize a national network of drop off centers, collection depots and regional processing centers operated by Waste Management and affiliated companies.

"We are excited to introduce eCycling as our branded nationwide electronics recycling service," stated Kevin McCarthy, director of Electronics Recycling for Waste Management Recycle America. "Our national network of collection and processing facilities continues to expand to provide enhanced customer convenience in an environmentally responsible manner."

Recycle America receives, sorts, disassembles as appropriate, consolidates and recycles electronics with an emphasis on domestic markets. Our goal is to reuse and recycle all of the material we collect and process. Only domestic markets are utilized for end of life products containing cathode ray tubes (CRTs).

This innovative project is a partnership among EPA Region III, Delaware, Maryland, Pennsylvania, Virginia, West Virginia and the District of Columbia to recycle unwanted computers, computer equipment, and televisions. Environmental officials in these states are working with the Electronics Industry Alliance, electronics retailers, waste management companies, and electronics recyclers on the project. More information on this exciting effort can be found at www.epa.gov/reg3wcmd/eCycling.htm.

National regulatory authorities have been handed the power to refuse to allow waste shipments to leave European Union ports or cross their territories via inland waterways, whether they represent the country sending a cargo, receiving it or being used for transhipment after a key ruling by the European Court of Justice.

Judges said that all EU member states had the duty to examine whether waste cargoes officially destined for recycling and recovery, (such as waste-for-energy schemes), were to be processed this way, or were actually earmarked for straight disposal, (such as landfilling), for which regulations allowing cross-border shipments are stricter.

While the German environmental authorities approved the shipment, the Austrians refused and the case was referred to the ECJ to rule whether under EU law, the state of the waste supplier could block such a movement. Lloyds List

The overvalued dollar is seriously affecting the U.S. forest products industrys global competitiveness, resulting in loss of domestic market share, dramatically lowered exports, plant closings and job losses, according to W. Henson Moore, president and CEO of the AFPA. He made this address during the annual Paper Week program.

The dollar is overvalued by 25-30 percent, a 16-year high, Moore noted. This is our number one issue, without question. It imposes a de facto tariff of 25-30 percent on U.S. producers selling into foreign markets, and enables foreign suppliers to outsell us in the domestic market.

Moore cited figures showing that in the 1997-2000 period, U.S. consumption of paper and paperboard products grew by 3.5 million tons, but imports captured more than 90 percent of that growth. Moreover, the U.S. trade deficit in paper and paperboard products ballooned from $273 million in 1997 to $3.8 billion last year.

In the last five years, U.S. paper companies have closed 72 mills and lost more than 32,000 jobs. Unless exchange rates are fixed pretty soon, and equilibrium is restored, the U.S. paper industry will not have the capacity to challenge our competitors and retake these lost markets.

Moore called on a variety of steps to help remedy the situation. Some of the steps include the following: a call on the Administration to adopt a public stance that the U.S. will not support an ever-higher value of the dollar beyond a sound level that is consistent with the economys underlying competitiveness.

Also, the AFPA asks that the government work with its trading partners at the G-8 meetings in June to address trade and currency imbalances as it did with the Plaza Accord of 1985. The U.S. must also confront countries that manipulate their currencies for commercial gain Japan being a prime example.

The production of newsprint by North American producers dropped 14.5 percent for January to 1.156 million metric tons. The decline was seen for both U.S. and Canadian mills. For the month U.S. producers saw production drop by 16.5 percent, while Canadian mills posted a 13 percent drop between the two months.

The sharp decline was due primarily to the significant amount of downtime being taken by newsprint mills throughout the continent. For January, the operating rate at North American newsprint mills stands at 85 percent of capacity, compared to last Januarys operating rate of 97 percent of capacity.

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