Real-Time Measurements and Characterization of Airborne Particulate Matter from a Primary Silicon Carbide Production Plant.

Rikke Jørgensen,Ida Kero

doi:10.3390/ijerph14121611

Abstract

Airborne particulate matter in the silicon carbide (SiC) industry is a known health hazard. The aims of this study were to elucidate whether the particulate matter generated inside the Acheson furnace during active operation is representative of the overall particulate matter in the furnace hall, and whether the Acheson furnaces are the main sources of ultrafine particles (UFP) in primary SiC production. The number concentration of ultrafine particles was evaluated using an Electrical Low Pressure Impactor (ELPITM, Dekati Ltd., Tampere, Finland), a Fast Mobility Particle Sizer (FMPSTM, TSI, Shoreview, MN, USA) and a Condensation Particle Counter (CPC, TSI, Shoreview, MN, USA). The results are discussed in terms of particle number concentration, particle size distribution and are also characterized by means of electron microscopy (TEM/SEM). Two locations were investigated; the industrial Acheson process furnace hall and a pilot furnace hall; both of which represent an active operating furnace. The geometric mean of the particle number concentration in the Acheson process furnace hall was 7.7 × 104 particles/cm3 for the UFP fraction and 1.0 × 105 particles/cm3 for the submicrometre fraction. Particulate matter collected at the two sites was analysed by electron microscopy. The PM from the Acheson process furnace hall is dominated by carbonaceous particles while the samples collected near the pilot furnace are primarily rich in silicon.

Highlights

Silicon carbide (SiC) is a hard, brittle, ceramic material used primarily for abrasives and cutting tools, but it is employed in a wide range of other applications, including electronics and diesel exhaust filters
The ultrafine particles (UFP) concentration geometric mean (GM) was 2.9 × 105 particles/cm3 measured by ELPI near the pilot furnace and 7.7 × 104 particles/cm3 measured by ELPI in the Acheson process furnace hall
1.0 × 105 particles/cm3 measured in the Acheson process furnace hall, which means that there is a factor of 4 difference between the concentrations in these two halls

Summary

Introduction

Silicon carbide (SiC) is a hard, brittle, ceramic material used primarily for abrasives and cutting tools, but it is employed in a wide range of other applications, including electronics and diesel exhaust filters. In an Acheson furnace, energy is generated by the resistive heating of a graphite core connected to two electrodes at each ends of the furnace. The furnace is built up as the raw materials, a mixture of coke (carbon) and a silica or quartz sand, are placed around the graphite core, as described by Smith et al [1] and by Smoak et al in the Encyclopedia of Chemical Technology [2]. The SiC develops as a solid cylindrical block, called ‘the crude’, around the core, with radial layers ranging from graphite as the inner material, over α-SiC (the highest grade material with a coarse crystalline, (hexagonal) structure), β-SiC, the so-called metallurgical grade SiC, partly reacted raw materials to the unreacted material on the outside. Public Health 2017, 14, 1611; doi:10.3390/ijerph14121611 www.mdpi.com/journal/ijerph

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