Study on the soluble and insoluble fume and hexavalent chromium emitted from a new covered electrode with micro and nano sized-sodium and potassium titanate-based flux.

Abstract

The present study discusses the effect of the addition of nano-sized arc stabilizing materials on fume emissions and its solubility characteristics. Micro and nano-sized sodium/potassium titanates were added to the SMAW electrode flux as a substitute for the conventional sodium and potassium silicate compounds. The total and soluble metal concentration of fumes from the newly developed electrodes were estimated and compared with that of commercially available electrodes. The estimation of fume formation rate and breathing zone concentration of fumes followed the ISO 15011-1 and ISO 10882-1 standard. An average 50% reduction in the soluble fraction of fumes was observed from the electrodes containing micro-sized potassium-titanate compounds, and the reduction was further improved by 60% when nano-sodium titanate was added to the flux. Whereas, the reduction in soluble metal concentration for potassium titanate coated electrodes were 45% and 55%, in that order, for their micro and nano-structured forms. The soluble fraction of hexavalent chromium from the electrodes containing 100% nano sodium/potassium titanates was reduced up to 50% in each impactor stage. The inclusion of nano-sized sodium titanate in the flux resulted in a reduction in fume formation rate up to 55% and breathing zone concentration of fumes by 58% compared to the conventional sodium silicate coated electrodes. The electrode assaying 100% nano-potassium titanate showed a reduction of 59% in fume formation rate and 61% in breathing zone concentration compared to that of conventional potassium silicate-coated electrodes.