Effects of milling on the metals analysis of soil samples containing metallic residues

Metallic residues are distributed heterogeneously onto small-arms range soils from projectile fragmentation upon impact with a target or berm backstop. Incremental Sampling Methodology (ISM) can address the spatially heterogeneous contamination of surface soils on small-arms ranges, but representative kilogram-sized ISM subsamples are affected by the range of metallic residue particle sizes in the sample. This study compares the precision and concentrations of metals in a small-arms range soil sample processed by a puck mill, ring and puck mill, ball mill, and mortar and pestle prior to analysis. The ball mill, puck mill, and puck and ring mill produced acceptable relative standard deviations of less than 15% for the anthropogenic metals of interest (Lead (Pb), Antimony (Sb), Copper (Cu), and Zinc (Zn)), with the ball mill exhibiting the greatest precision for Pb, Cu, and Zn. Precision by mortar and pestle, without milling, was considerably higher (40% to >100%) for anthropogenic metals. Media anthropogenic metal concentrations varied by more than 40% between milling methods, with the greatest concentrations produced by the puck mill, followed by the puck and ring mill and then the ball mill. Metal concentrations were also dependent on milling time, with concentrations stabilizing for the puck mill by 300 s but still increasing for the ball mill over 20 h. Differences in metal concentrations were not directly related to the surface area of the milled sample. Overall, the tested milling methods were successful in producing reproducible data for soils containing metallic residues. However, the effects of milling type and time on concentrations require consideration in environmental investigations.

XRD and SEM Analyses of Bulk Ga-Doped Li7La3Zr2O12 Li- Ion Conducting Solid Electrolyte Prepared via Hot-Pressing Method

In this study, bulk lithium-ion conducting solid electrolyte of Ga-doped Li7La3Zr2O12 (Li7-3XGaxLa3Zr2O12) where x = 0.1 (Ga-LLZO) was prepared via hot pressing at 500 °C. Precursor powder for hot-pressing was prepared using conventional solid state reaction method. Planetary ball milling was employed to investigate the particle size effect on the structure and densification of hot-pressed samples. XRD patterns of the bulk hot-pressed sample revealed a crystalline phase of which the major peaks observed can be indexed to a cubic LLZO structure; however, a major impurity phase of La2Zr2O7 was observed for the ball-milled sample. Thermogravimetric and differential thermal analysis showed about 12% weight loss below 900 °C which may have affected the observed hot-pressing structure. Although lower density measurement and an impurity phase of La2Zr2O7 were observed for the ball-milled sample, ball-milling also resulted to a more homogeneous and finer particle size as shown by SEM images results.

Hydriding and Dehydriding Features of a Titanium-Added Magnesium Hydride Composite

Magnesium has excellent hydrogen-storage properties except low hydriding and dehydriding rates. In the present work, titanium (Ti) was chosen as an additive to increase the hydriding rate of Mg and the dehydriding rate of MgH2. 15 wt.% Ti was added to MgH2 by milling in hydrogen (reactive mechanical grinding). The hydriding and dehydriding features of the Ti-added MgH2 composite (named 85 MgH2 + 15 Ti) were investigated. At the first cycle (n = 1), 85 MgH2 + 15 Ti absorbed 2.96 wt.% H for 2.5 min and 5.51 wt.% H for 60 min at 593 K in 12 bar H2, having an effective hydrogen-storage capacity of 5.51 wt.%. β-MgH2, γ-MgH2, TiH1.924, MgO, and MgTi2O4 were formed during reactive mechanical grinding. Reactive mechanical grinding of MgH2 with Ti is believed to create imperfections, produce cracks and clean surfaces, and decrease particle sizes. The phases formed during reactive mechanical grinding and their pulverization during reactive mechanical grinding are believed to make these effects stronger. Since the γ-MgH2 phase is believed to be decomposed at n = 1, the existence of the γ-MgH2 phase in the milled sample does not contribute to the improvement of the sorption behavior of Mg.

ANALISIS SIFAT MAGNETIK DAN STRUKTUR PARTIKEL PASIR BESI PANTAI ARTA PARIAMAN SUMATERA BARAT MENGGUNAKAN BALL MILLING

Analisys of magnetic properties and structure of particles of iron sand of Arta, Pariaman beach West Sumatra. Has been conducted the iron sand samples were dried, then the iron sand separation process was carried out using Iron Sand Separator (ISS). Next, the sample was milled for 30, 60 and 90 hours. The separation between magnetic particles and non magnetic particles was done using Neodymium Iron Boron (NdFeB) magnet. Magnetic induction measurements were carried out using Pasco PS-2162 Magnetic Probe which measured the total magnetic induction of solenoid (solenoid with core sample and milled sample(consentrate II)) as a function of electric current of 1-8 A for a fixed distance of 1 mm. Identification of the content of elements contained in iron sand before and after processing with Ball Milling for 90 hours was carried out using X-Ray Fluorescence (XRF). The phase of magnetic particles processed by Ball Milling was determined using X-Ray Diffraction (XRD). The calculation results show that the magnetic susceptibility of the sample increases with increasing Ball Milling time, from (69426,19 × 10-5 – 80332,13 × 10-5). These values are in the interval 220 - 380.000 × 10-5of the Ilmenite mineral. The magnetite phase appears more than the maghemite phase and the hematite phase after Ball Milling for 90 hours. The particle size of magnetik particle decreases as milling time increase, this trend is confirmed by the result of XRD.

Structure and catalytic behaviour of CuO–CeO 2 prepared by high-energy ball milling

The aim of this study is to prepare CuO–CeO 2 composite by means of mechanical milling and to investigate its characteristics as a catalyst. The structural and morphological features of milled samples are observed by X-ray diffractometry and scanning electron microscopy. The redox property and total OSC (oxygen storage capacity) of the milled sample were measured by using GC-TCD and TG-DTA, which are important parameters to indicate the effectiveness of catalysts. Interestingly, reduction of CuO is repeatedly observed when milling of CuO–CeO 2 powder mixture is processed in air. The redox property of milled CuO–CeO 2 sample is investigated by H 2 -TPR, where three reduction peaks are observed for 0 h milling and only one broad peak for various other milling times. The total OSC of mechanically driven CuO–CeO 2 catalyst is much higher than that of the CeO 2 –ZrO 2 traditional catalyst system at low temperatures.

Effect of additives, ball milling and isotopic exchange in porous magnesium borohydride

Specific surface area measurements (BET) of as received and ball milled samples showed the collapse of the porous network after milling, while a heat treated ball milled sample regained most of its porous γ-Mg(BH4)2 structure.

Carbothermic reduction of mechanically activated NiO-carbon mixture: Non-isothermal kinetics

The effect of mechanical activation on the carbothermic reduction of nickel oxide was investigated. Mixtures of nickel oxide and activated carbon (99% carbon) were milled for different periods of time in a planetary ball mill. The unmilled mixture and milled samples were subjected to thermogravimetric analysis (TGA) under an argon atmosphere and their solid products of the reduction reaction were studied using XRD experiments. TGA showed that the reduction of NiO started at ~800? and ~720? in un-milled and one-hour milled samples respectively whilst after 25h of milling it decreased to about 430?. The kinetics parameters of carbothermic reduction were determined using non-isothermal method (Coats-Redfern Method) for un-milled and milled samples. The activation energy was determined to be about 222 kJ mol-1for un-milled mixture whilst it was decreased to about 148 kJ mol-1 in 25-h milled sample. The decrease in the particle size/crystallite size of the milled samples resulted in a significant drop in the reaction temperature.

Characterization and Fabrication of Metakaolin using Pulau Bangka Kaolin

Geopolymer material is an advanced material that is now being looked for its use as a refractory material, additive for building material, as well as other applications. Geopolymer is produced by polymerizing the precursor used in the process. One of the common precursors being used as geopolymer is metakaolin. The metakaolin was produced by thermal treatment (calcination) of kaolin minerals, which will convert its mineral structure from crystaline into amorphous and make it more reactive. This paper presents the fabrication and characterization of metakaolin using kaolin from Bangka island. The main structure of kaolin used in this study are kaolinite and muscovite according to XRD results obtained. Metakaolin was produced by thermal treatment using three different calcination temperatures ranged from 600 to 700°C and calcined for 4 hours. Prior to calcination, some specimens will be mechanically milled using planetary ball mill for 15 minutes with the milling speed of 20.00 rad/s and will also be calcined with the same parameter. As a comparison, commercial metakaolin MetaStar also be used to compare it to all metakaolin produced. All metakaolin produced are characterized by XRD and SEM, and STA test will be performed to kaolin to examine its thermal behavior. The STA test performed to both milled and non-milled sample shows that dehydroxylation and reconstruction process occurs at temperature range of 460-520°C and 520-640°C for kaolin sample, and at temperature of 426-537°C and 537-618°C for milled kaolin sample. XRD pattern obtained shows that almost all metakaolin produced have the relatively similar pattern to each other as well as to MetaStar, with the main peak of quartz (SiO2) at 2= 26.60° to 26.65°. The SEM results shows the characteristic layered-laminate plate-like structure of kaolin. Compared to another SEM results obtained, it can be concluded that there are no changes to the visible structure of metakaolin produced with the same kaolin used after calcination.

Synthesis by High-Energy Ball Milling of MgH2-TiFe Composites for Hydrogen Storage

The aim of this work is to investigate the influence of some processes variables on the microstructure and hydrogen absorption kinetics of MgH2 - X wt.% TiFe composites. Samples were synthesized by high-energy ball milling in a planetary (X = 40, 50, 60) and shaker mill (X = 40) under high-purity argon atmosphere. Commercial MgH2 instead of Mg powder was used in order to reduce adherence on the vial and balls. TiFe powder was previously produced by ball milling a mixture of TiH2 and Fe powders followed by a reaction synthesis at 600oC. Milled composites samples were characterized by XRD and SEM analysis. Milling time was preliminary investigated (X = 40) in the planetary ball mill (6 to 36h). TiFe particle size reduction was shown to be difficult since they are surrounded by MgH2 matrix. Strong particle reduction was obtained by using a shaker mill only for 2 hours and adding cyclohexane as process control agent. No reaction between MgH2 and TiFe compound was observed in any milled sample. Hydrogen absorption kinetics measurements of the as-milled samples were conducted on an Sieverts' type apparatus at room temperature after hydrogen desorption at 350oC under vacuum. The best hydrogen kinetics (3 wt% at the first hour) was attained by the planetary milled sample (36 h). Higher hydrogen capacity was observed for the sample milled in the shaker mill (4.0 wt.%), but only after 13h.

Post-anneal effect on the structural and Li+ conduction properties in NaI - LiBH4 system

ABSTRACTIn the present work, NaI – LiBH4 system fabricated by ball milling were post annealed and their variation of Li+ ion conductivity were investigated. From the change of lattice parameters by post annealing, it was suggested that unreacted LiBH4 existed in as-milled sample further dissolved into NaI, which implied an enhancement of the sample homogeneity. On the other hand, the segregation of LiI was anticipated when ball milled 15NaI·LiI (BH4 free sample) was annealed at 423 K. Li+ conductivity was decreased by post anneal process and compositional dependence of an activation energy for Li+ conduction was indicated for the homogeneous NaI – LiBH4 system.