Bekele, Tesfaye Ayele (2015) Recycling Plaster of Paris from Discarded Gypsum Moulds for Tabor Ceramics Products Manufacturing Share Company. Masters thesis, Addis Ababa University.
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Abstract
A considerable amount of waste plaster of Paris or gypsum mould is produced in the pottery, and sanitary ware industries. Conventionally, this waste product has usually been disposed of in landfill sites and the like. This is becoming uneconomical due to the increasing cost of gypsum and particularly with diminishing productivity of some sources of gypsum, and also the introduction of landfill taxes. This thesis research seeks to address this problem by recycling plaster of Paris from discarded gypsum mould. The study has been conducted in such a way that, first discarded gypsum mould samples collected from Tabor ceramics products factory was washed and sieved to remove dust and soluble deflocculates. The result showed 8.4% impurity content. The mole of water of crystallization of the sample before calcination was found to be 1.943 and this proved that it was in a dihydrate state since mole of water of crystallization of dihydrate gypsum is 2. Following the same procedure, calcination of the sample at a temperature of 148.5oC for 2.2 hours resulted in mole of water of crystallization of 0.45 and this proves conversion to hemihydrate state since mole of water of crystallization of hemihydrate plaster is 0.5. The recycled powder regained whitish color with a rise in temperature starting from a calcination temperature of 140oc. The experimental design and statistical analysis was done by Design-Expert 7.0.0 program. From the result of analysis, maximum setting time was found to be 19.3 minutes at calcination temperature of 1450c and calcination time of 3 hours. All values of water absorption are well within the working ranges of the factory. The highest value of compressive strength obtained is 5.7010 MPa at calcination temperature of 148.50C and calcination time of 2.15 hours.The optimization analysis gives a setting time value of 15 minutes, water absorption 0.25cm/minute and compressive strength value of 5.7011MPa at 148.5oC calcination temperature and 2.22 hours calcination time. The result of the blending experiment shows that blending generally increases the compressive strength and a maximum of 8.6956MPa is obtained when 60% recycled plaster of paris is mixed with 40% vergin plaster of paris. Finally, the plant is financially evaluated and its initial investment cost will be recovered fully within two operation years which makes the plant viable
| Item Type: | Thesis (Masters) |
|---|---|
| Uncontrolled Keywords: | Chemical and Bio Engineering |
| Subjects: | Q Science > Q Science (General) Q Science > QD Chemistry T Technology > T Technology (General) T Technology > TP Chemical technology |
| Divisions: | Africana |
| Depositing User: | Andriamparany Edilbert RANOARIVONY |
| Date Deposited: | 09 Aug 2018 14:24 |
| Last Modified: | 09 Aug 2018 14:24 |
| URI: | http://thesisbank.jhia.ac.ke/id/eprint/8087 |
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