silicon and ferrosilicon

Unique quantitative bioaccessibility data has been generated, and the influence of surface/material and test media characteristics on the elemental release process were assessed for silicon containing materials in specific synthetic body fluids at certain time periods at a fixed loading. The metal release test protocol, elaborated by the KTH team, has previously been used for classification, ranking, and screening of different alloys and metals. Time resolved elemental release of Si, Fe and Al from particles, sized less than 50 µm, of two grades of metallurgical silicon (high purity silicon, SiHG, low purity silicon, SiLG), an alloy (ferrosilicon, FeSi) and a mineral (aluminium silicate, AlSi) has been investigated in synthetic body fluids of varying pH, composition and complexation capacity, simple models of for example dermal contact and digestion scenarios. Individual methods for analysis of released Si (as silicic acid, Si(OH)4) in synthetic body fluids using GF-AAS were developed for each fluid including optimisation of solution pH and graphite furnace parameters. The release of Si from the two metallurgical silicon grades was strongly dependent on both pH and media composition with the highest release in pH neutral media. No similar effect was observed for the FeSi alloy or the aluminium silicate mineral. Surface adsorption of phosphate and lactic acid were believed to hinder the release of Si whereas the presence of citric acid enhanced the release as a result of surface complexation. An increased presence of Al and Fe in the material (low purity metalloid, alloy or mineral) resulted in a reduced release of Si in pH neutral media. The release of Si was enhanced for all materials with Al at their outermost surface in acetic media.

Topics: Alloys; Hydrogen-Ion Concentration; Minerals; Models, Chemical; Particle Size; Protons; Silicates; Silicon; Silicon Compounds

Silica fume (SF) is an inorganic waste material which is generated during the elemental silicon and ferro-silicon alloy production. Due to the unique properties, it is utilized in several industries. However, very little information is available on the utilization potential of SF in traditional clay brick industry. In this study, the effect of different quantities of SF addition on the properties of fired clay brick was investigated. Test samples were produced by uniaxial pressing and fired at 800, 900, 1000 and 1100 degrees C. The microstructures of the samples were investigated by Scanning Electron Microscopy (SEM). The strength of the fired samples at 1000 and 1100 degrees C were significantly improved with SF addition. It was concluded that the reactive amorphous nature of SF particles enhances the sintering action locally and this gives better strength behaviour. SF addition also improved the efflorescence behaviour of the bricks. It was concluded that the effect of SF addition on the fired clay brick mainly depends on the firing temperature. At low firing temperatures, SF addition has a tendency to decrease the bulk density. However at higher firing temperatures, SF addition allows better sintering action with a drastic increase in bulk density.

Topics: Absorption; Alloys; Aluminum Silicates; Clay; Construction Materials; Materials Testing; Microscopy, Electron, Scanning; Porosity; Silicon; Silicon Compounds; Temperature; Waste Management

Topics: Aged; Chromium; Chromium Alloys; Humans; Lung Neoplasms; Male; Middle Aged; Neoplasms; Norway; Occupational Diseases; Prostatic Neoplasms; Silicon; Silicon Compounds

Topics: Dust; Iron; Silicon; Silicon Compounds