engleski

RHEOLOGICAL PROPERTIES OF WATER-BASED ALUMINA SUSPENSIONS IN RECYCLING WASTE ALUMINA POWDER

Waste, i.e. secondary alumina (Al₂O₃) ceramic powder is produced when green bodies are machined prior to the sintering of ceramic products. This industrial waste, although non-hazardous, has to be disposed of using the legally adequate methods. Typically, landfills are used for this purpose, which presents additional manufacturing costs. This paper focuses on how to recycle waste alumina by slip casting of alumina water-based suspensions. Slip casting process requires limited suspension viscosity. When virgin alumina powder is substituted with waste alumina powder, the suspension viscosity increases. This paper presents the results of studying the influence of adding commercially available dispersant on apparent viscosity of suspensions with 60 wt.% of solid loading. There were three different solid samples studied: 30, 45 and 60 wt.% of waste alumina, as expressed by total dry weight.The water-based Al₂O₃ suspension were homogenized by a planetary ball mill, after which the suspension stability was tested to rheological properties. The tests have showed that in aqueous ceramic suspensions with up to 60 dry wt.% solid component it is possible to achieve favorable viscosity for slip casting when 0.06 dwb.% of the dispersant Tiron is added. The increase in waste alumina content caused a gradual increase in the apparent viscosity. Suspensions with more than 60 :40 ratio of waste to virgin alumina powder become unusable for slip casting due to too high viscosity.

Recycling, waste, alumina, rheology, viscosity

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