Chemical behavior of nickel sulfide in soda-lime-silica glass melts

摘要

Nickel sulfide formation form nickel-containing steel residuals in the glass batch has been assumed for quite some time.Melting trials were carried out with a soda-lime-silica glass batch containing steel particles with 20% nickel.By this the above assumption was whown to be true and the exact cascade of the reaction of the metals with the sulfuate of the glass melt could be pointd out.Five steps canbe distinguished:sweating out the less noble elements (chromium,manganese,carbon);formation of a mixed iron nickel sulfide phase in equilibrium with the remaining iron nickel alloy;enrichment of nickel in thealloy and the sulfide phase,until complete elimination of iron;sulfidation of the remaining pure nickel and formation of a nickel-rich sulfide;oxidation to NiS.The reactioncascade found experimentally is confirmed by the authors'own thermodynamic calculations.Literature data show that nickel sulfides containing more sulfur than the 1:1 composition arenot stablein the glassmelt and decompose in a small"explosion".The exact composition of an NiS stone found in glass depends on its individual temperature/time history.It consits mainly of(Ni,Fe)S,which may transform to millerite.If the former sulfide melt still contains a nickel excess,the crystalline stone may also contain minor partsof other Ni_yS_x phases such as Ni_9S_8 or Ni_7S_6.