Synthesis of Fe_3O_4 nanoparticles by wet milling iron powder in a planetary ball mill

Fe3O4 nanoparticles with sizes ranging from 30 to 80 nm were synthesized by wet milling iron powders in a planetary ball mill. The phase composition and the morphologies of the as-synthesized products were measured by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. Nanosized Fe3O4 particles were prepared by wet milling metallic iron powder （-200 mesh, 99%） in a planetary ball mill equipped with stainless steel vials using iron balls under distilled water with a ball-to-powder mass ratio of 50：1 and at a rotation speed of 300 rpm. The use of the iron balls in this method played a key role in Fe3O4 formation. The present technique is simple and the process is easy to carry out.

Recovery of iron from waste ferrous sulphate by co-precipitation and magnetic separation

Magnetite concentrate was recovered from ferrous sulphate by co-precipitation and magnetic separation. In co-precipitation process, the effects of reaction conditions on iron recovery were studied, and the optimal reaction parameters are proposed as follows： n（CaO）/n（Fe2＋） 1.4：1, reaction temperature 80 ℃, ferrous ion concentration 0.4 mol/L, and the final mole ratio of Fe3＋ to FJ＋ in the reaction solution 1.9-2.1. In magnetic separation process, the effects of milling time and magnetic induction intensity on iron recovery were investigated. Wet milling played an important part in breaking the encapsulated magnetic phases. The results showed that the mixed product was wet-milled for 20 min before magnetic separation, the grade and recovery rate of iron in magnetite concentrate were increased from 51.41% and 84.15% to 62.05% and 85.35%, respectively.

Effect of element fitting on composition optimization of Al-Cu-Ti amorphous alloy by mechanical alloying

In order to minimize the crystal phase in Al-Cu-Ti amorphous powder,Al65Cu35-xTix amorphous powders were optimized via ball milling through adjusting the amount of Cu and Ti elements and the ball milling time.The results show that increasing the mole fraction of Ti can decrease the amount of Al Cu2Ti,Cu9Al4,and Al2Cu intermetallics formed during the process of ball milling;and prolonging the ball milling time can reduce the element crystalline phase to almost none.The optimal composition is determined to be Al65Cu16.5Ti18.5.TiH2 forms in all selected Al65Cu35-xTix amorphous powders during the process of optimization.H atom is decomposed from toluene and reacts with Ti during ball milling,leading to the formation of TiH2.The volume fraction of TiH2 in Al65Cu16.5Ti18.5 amorphous powder is measured to be 4.30%.

Preparation and Application of Light-weight Raw Materials Using Natural Forsterite

In order to develop new basic light-weight refractory raw materials,natural forsterite(<0.045 mm)and magnesite(<0.045 mm)were batched according to the chemical composition of forsterite(2MgO·SiO_(2)),wet milled,semi-dry molded and calcined at different temperatures.Then cylinder samples with diameter of 36 mm were prepared.The effects of the wet milling jar rotation speed,the calcination temperature and the anthracite addition on the properties of the samples were researched.The results show that:when the calcination temperature exceeds 1300℃,all the mineral phases have converted to the desired phases;with the increase of the rotation speed and the calcination temperature,the bulk density of the samples increases,the apparent porosity decreases and the compressive strength improves.By comprehensive consideration,400 r·min^(-1) and 1450℃ are taken as the optimal scheme.High addition of anthracite makes the samples light,so series of light-weight raw materials with uniformly distributed micro-pores can be gained.The light-weight raw materials achieved were used for insulation refractory castables,obtaining good application.

Recovery of magnetite from waste ferrous sulfate using polyethylene glycol(PEG) as a dispersant

The effect of PEG dispersant on the magnetic separation of magnetite（Fe3O4） synthesized from ferrous sulfate solution via co-precipitation method with calcium hydroxide as the precipitant was investigated. The results indicated that a PEG dispersant could significantly affect Fe3O4 recovery. Adding PEG during the preparation of Fe3O4 was unfavorable for Fe3O4 recovery. When the PEG-6000 concentration was increased from 0 to 8 g/L, the iron grade and median particle size of the Fe3O4 product decreased from 65.58% and 2.35 μm to 57.79% and 1.35 μm, respectively. However, adding PEG during the wet milling of the mixed product promoted the subsequent recovery of Fe3O4. When the amount of PEG-200 increased from 0% to 4% of the powder mass, the grade of iron in the Fe3O4 product increased from 65.58% to 68.32%. While the relative molecular mass of PEG at an amount of 4% of the powder mass increased from 200 to 20000, the grade of iron was reduced from 68.32% to 66.70%.

Wet-milling synthesis of immobilized Pt/Ir nanoclusters as promising heterogeneous catalysts

Being a typical state of the art heterogeneous catalyst,supported noble metal catalyst often demonstrates enhanced catalytic properties.However,a facile synthetic method for realizing large-scale and low-cost supported noble metal catalyst is strictly indispensable.To this end,by making use of the strong metal-support interaction(SMSI)and mechanochemical reaction,we introduce an efficient synthetic route to obtain ultrafine Pt and Ir nanoclusters immobilized on diverse substrates by wet chemical milling.We further demonstrate the scaling-up effect of our approach by large-scale ball-milling production of Pt nanoclusters immobilized on TiO_(2)substrate.The synthesized Pt/Ir@Co_(3)O_(4)catalysts exhibit superior oxygen evolution reaction(OER)performance with only 230 and 290 mV overpotential to achieve current density of 10 and 100 mA·cm^(-2),beating the catalytic performance of Co_(3)O_(4)supported Pt or Ir clusters and commercial Ir/C.It is envisioned that the present work strategically directs facile ways for fabricating supported noble metal heterogeneous catalysts.

Dry ball milling and wet ball milling for fabricating copper-yttria composites

Yttria-reinforced copper matrix composites were prepared by dry ball milling （DBM） and wet ball milling （WBM）, respectively, followed by spark plasma sintering （SPS）. It is to determine which milling process is better for fabricating Cu-Y2O3 composites. It is found that Cu-Y2O3 composites synthesized by DBM exhibit better densification, mechanical and electrical properties than those by WBM. Less agglomeration of reinforcements in the bulk composites by DBM is responsible for the better perfor- mances. To further understand the reason of less agglomeration of Y2O3 in the bulks by DBM, morphologies of prepared powders were investigated and analyzed. Higher ball＇s impact energy and the formation of copper oxide on the matrix surface during DBM process contribute to small matrix particles, which is beneficial for less agglomeration.

Preparation of stable colloidal suspensions of superdisintegrants via wet stirred media milling

Superdisintegrants are cross-linked polymers that can be used as dispersants for fast release of drug nanoparticles from nanocomposite microparticles during in vitro and in vivo dissolution. Currently avail- able superdisintegrant particles have average sizes of approximately 5-130 μm, which are too big for drug nanocomposite applications. Hence, production of stable superdisintegrant suspensions with less than 5 μm particles is desirable. Here, we explore the preparation of colloidal suspensions of anionic and nonionic superdisintegrants using a wet stirred media mill and assess their physical stability. Sodium starch glycolate （SSG） and crospovidone （CP） were selected as representative anionic and nonionic superdisintegrants, and hydroxypropyl cellulose （HPC） and sodium dodecyl sulfate （SDS） were used as a steric stabilizer and a wetting agent/stabilizer, respectively. Particle sizing, scanning electron microscopy, and zeta potential measurements were used to characterize the suspensions. Colloidal superdisintegrant suspensions were prepared reproducibly. The extensive particle breakage was attributed to the swelling-induced softening in water. SSG suspensions were stable even in the absence of stabilizers, whereas CP suspensions required HPC-SDS for minimizing particle aggregation. These findings were explained by the higher absolute （negative） zeta potential of the suspensions of the anionic superdisintegrant （SSG） as compared with those of the nonionic superdisintegrant （CP）.

Ultrasonic attenuation spectroscopy for multivariate statistical process control in nanomaterial processing

Ultrasonic attenuation spectroscopy （UAS） is an attractive process analytical technology （PAT） for on-line real-time characterisation of slurries for particle size distribution （PSD） estimation. It is however only applicable to relatively low solid concentrations since existing instrument process models still cannot fully take into account the phenomena of particle-particle interaction and multiple scattering, leading to errors in PSD estimation. This paper investigates an alternative use of the raw attenuation spectra for direct multivariate statistical process control （MSPC）. The UAS raw spectra were processed using principal component analysis. The selected principal components were used to derive two MSPC statistics, the Hotelling＇s T2 and square prediction error （SPE）. The method is illustrated and demonstrated by reference to a wet milling process for processinR nanoparticles.

Mechanically induced phase transformation of zinc sulfide

Molecular dynamics （MD） simulations of the consecutive compression-decompression cycles ot hexagonal zinc sulfide （wurtzite） nanoparticles predict an irreversible phase transformation to the cubic polymorph.The phase transformation commences at the contact area between the particle and the inden- ter and proceeds with the number of compression cycles. Dislocations are visible for a particle size above 5nm. Results from wet grinding and dry powder compression experiments on a commercial wurtzite pigment agree qualitatively with MD simulation predictions. X-ray diffraction patterns reveal that the amount of cubic polymorph in the compressed samples increases with pressure applied to the powder. In comparison with powder compression, wet milling leads to a more pronounced phase transformation. This occurs because the particles are exposed to a large number of stress events by collision with the grinding media, which leads to the formation of defects and new surface crystallites by particle fracture. According to the MD simulations, phase transformation is expected to occur preferentially in surface crystallites because they experience the highest mechanical load. Because of the phase transformation, the wet ground and compressed samples exhibit a lower photo- luminescence intensity than the feed material. In comparison with powder compression, milling reduces the photoluminescence intensity more substantially. This occurs because a higher defect concentration is formed. The defects contribute to the phase transformation and photoluminescence quenching.

Insights on pretreatment of Indian hematite fines in grate-kiln pelletizing process： the choice of grinding processes

Indian hematite fines are normally characterized by high iron grade and minor impurities, which are usually used for sinter fines. With macroscale operations technology of blast furnace in Indian, pellets, as a kind of high-quality materials, attract more and more attention. However, the hematite fines possess the coarse size. Hence, they inevitably need to be further finely ground for pelletizing before balling. The grinding behavior of Indian hematite fines was revealed by conducting the ball milling tests and determining the Bond ball mill work index （Wi）. The results show that Indian hematite fines have an excellent grindability with Wi of only 7.40-7.73 kWh/t, indicating that ball milling is an economically viable way to pretreat Indian hematite fines. Nonetheless, due to poor sedimentation and filtering properties of wet ground products, the dry ball milling is more appropriate to process Indian hematite fines. In addition, the superior quality green balls can be manufactured with dry ground products under the conditions of 0.5% bentonite dosage, 7.5% moisture and balling for 12 min, which further confirmed that the recommended pellet feed preparation technique is reasonable.