Mechanism of Potassium Release from Feldspar by Mechanical Activation in Presence of Additives at Ordinary Temperatures.

To improve the potassium availability of feldspar at ordinary temperatures, the mechanical grinding and addition of sodium hydroxide/salts were employed to study the effects of mechanical activation and strong alkali addition on particle characteristics, water-soluble potassium, and the available potassium of feldspar. A laser particle size analyzer was utilized for the direct determination of particle size distribution (PSD) using ground samples. The Brunauer-Emmett-Teller (BET) method was employed for specific surface areas. X-ray diffraction (XRD) was employed for structural characterization, scanning electron microscopy (SEM) for morphology exploration, and energy dispersive spectroscopy (EDS) to determine the chemical composition of potassium feldspar powder. The results revealed that the mechanical activation of potassium feldspar could reduce the particle size and produce agglomerated nanoparticles in the later period. The addition of NaOH and sodium salt did not cause agglomeration, and NaOH dissolved the nanoparticles. The water-soluble potassium content of feldspar in each treatment increased during mechanical grinding, from 21.64 mg kg-1 to 1495.81 mg·kg-1, by adding NaOH 5% weight of potassium feldspar powder and to 3044.08 mg·kg-1 by adding NaOH 10% weight with effects different from those of mechanical shaking. By comparison, only 162.93 mg·kg-1 water-soluble potassium was obtained by adding NaOH 5% weight. The dissolved potassium in the former case was significantly higher than in the latter, and the addition of NaOH and sodium salts significantly enhanced the water-soluble potassium contents due to ion exchange. Furthermore, the addition of sodium hydroxide improved the water-soluble potassium due to its mechanochemical action on potassium feldspar. The mechanical energy changed the crystal structure of potassium feldspar, explaining the increase in available potassium. The addition of sodium salts did not promote change in the feldspar's structure, thereby did not raise the available potassium content. The reason for this was related to the mechanochemical action on sodium hydroxide and feldspar, which could promote the dissolution of fine particles, thereby incrementing the available potassium.

Characteristics of ultrafine-ground potassium-bearing shale and the effects of roasting pre-cracking.

Potassium-bearing shale is being developed as a potential alternative to potash for use in fertilisers. The first step in this process is to reduce its particle size by crushing. This paper explores whether roasting pre-cracked potassium-bearing shale can improve the quality of the resulting ultrafine product. Analysis of the particle size distribution of the ultrafine product and its fractal dimension found contradictory results: the minimum particle size distribution was obtained by roasting for 2.5 h, while the minimum fractal dimension was obtained by roasting for 1 h. Fuzzy comprehensive evaluation was conducted with three indicators-(1) the weight of the - 10 µm product, (2) the fractal dimension of the particle size distribution, and (3) d97-to obtain a unique combination of indicators that reflects the quality and quantity of the products. The weights of the three indicators were calculated by an analytic hierarchical process to be 0.69, 0.149 and 0.161, respectively. Roasting pre-cracked shale for 2-2.5 h was found to improve the mean values of the fuzzy comprehensive evaluation indicators by about 0.07. However, the cost increased from 2.82 RMB to ≥ 10.08 RMB, which is not feasible for widespread industrial implementation.

A High Performance Lithium-Ion Capacitor with Both Electrodes Prepared from Sri Lanka Graphite Ore.

The natural Sri Lanka graphite (vein graphite) is widely-used as anode material for lithium-ion batteries (LIBs), due to its high crystallinity and low cost. In this work, graphitic porous carbon (GPC) and high-purity vein graphite (PVG) were prepared from Sri Lanka graphite ore by KOH activation, and high temperature purification, respectively. Furthermore, a lithium-ion capacitor (LIC) is fabricated with GPC as cathode, and PVG as anode. The assembled GPC//PVG LIC shows a notable electrochemical performance with a maximum energy density of 86 W·h·kg-1 at 150 W·kg-1, and 48 W·h·kg-1 at a high-power density of 7.4 kW·kg-1. This high-performance LIC based on PVG and GPC is believed to be promising for practical applications, due to its low-cost raw materials and industrially feasible production.

Synthesis of morphology-controlled ZnO microstructures via a microwave-assisted hydrothermal method and their gas-sensing property.

Controllable ZnO architectures with flower-like and rod-like morphologies were synthesized via a microwave-assisted hydrothermal method. By adjusting the concentration of Zn(2+) in the aqueous precursors, different morphologies of ZnO microstructures were obtained. The size of ZnO was uniform after ultrasonic treatment. The growth process of ZnO in solution was studied by monitoring the intermediate products, which were extracted at different stages of the reactions: (i) precursor preparation, (ii) microwave irradiation heating, (iii) natural cooling. Studies of the SEM images and XRD data revealed that the formation of ZnO occurred via in situ assembly or dissolution-reprecipitation of zinc hydroxide complexes. The morphology-dependent ethanol sensing performance was observed; the seven-spine ZnO structures exhibit the highest activity.

Surface modification of purified fly ash and application in polymer.

With the growing general concern about the pollution by fly ash (FA), there has been global interest in its utilization. Purified FA or FA micro-beads are suitable as polymer filling materials because of their density, good dispersity and fluidity of globular particles. However, FA as a filler has not been widely used up to now on account of low whiteness values and low friction of untreated FA surface. In order to improve the FA quality, a surface modification method by using isothermal heating is proposed in this paper. Preparation of composite fly ash (CFA) in the Ca(OH)(2)-H(2)O-CO(2) system is described. Good coating results on FA surfaces can be achieved under suitable operating parameters. The characteristics of CFA are discussed and analyzed based on data from X-ray diffraction, scanning electron microscopy (SEM), infrared spectra, and BET multiple-point nitrogen adsorption method. Feedstocks with less than 45 microm grain size, 2.86 m(2) g(-1) specific surface area, and 36.68 whiteness value revealed an increase in specific surface area ranging from 8.69 to 10.01 m(2) g(-1) and an increase in whiteness values ranging from 63.67 to 73.13 after coating. A SEM study allowed a detailed determination of the morphology of the surface roughness. Filling tests also show that a rough surface of the CFA enhances contact opportunities and improves the interface between polymer and CFA blended with polypropylene (PP).