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| dc.contributor.author | Melkamu, Zekariyas | |
| dc.contributor.author | Belachew, Ayenew | |
| dc.contributor.author | Chilot, Habtamu | |
| dc.date.accessioned | 2020-08-13T06:20:30Z | |
| dc.date.available | 2020-08-13T06:20:30Z | |
| dc.date.issued | 2018 | |
| dc.identifier.uri | http://hdl.handle.net/123456789/11123 | |
| dc.description.abstract | The objective of this thesis work is producing dustless chalk from easily available raw materials pop. Chalk is a soft, porous, sedimentary carbonate rock, a form of limestone composed of the mineral calcinated which is ionic salt called calcium carbonate CaCO3. In Ethiopia, there is locally available raw material pop which is extracted from (gypsum, CaSO4.2H2O) that used for the production of chalk. Chalk is produced in Ethiopia which is dusty and less quality of product and the chalk available in the markets are not eco-friendly with the environment because of its more soiling of the hands, the particle float in the air and enters in the human body and also sound create during writing in the blackboard. So to reduce these risks it is better to produce dustless chalk. The main raw material which is Plaster of Paris was collected from the market. The raw materials used for the production of dustless chalk were calcined gypsum (Plaster of Paris), calcium carbonate and starch powders. It was made by using chalk mould after the proper mixing of the above raw materials with water. The moulder accommodates 20 chalk sticks per batch. The slurry was quickly poured into the mould without any delay and the resident time is (1-2) min. The solution was allowed to stay in the mould for 15-20 minutes for the first stage of drying to take place and open the mould and loosen the plastics which contains the chalks when sure that the solution (chalk) has formed. The dustless chalk writes smoothly without scratch, while the normal chalk leaves some scratch on the board and the dustless chalk have less soiling of hand compared to normal chalk, the particles of the dust less chalk are tend to land rather than floating in the air. From experimental result, when the mass starch is lower the chalk is hard and dusty. Consequently when the mass of starch is high the chalk is very soft and the particles are compacted to each other and it is not more comfortable to write on the black The data were analyzed to determine optimum conditions for testing response parameters such as mass of caco3 (10,20 and30gm), mass of starch(5,10 and 15gm)and drying temperature (100, 110and 120 oC) to get the responses bulk density((1.121 - 1.201g/cm3) and moisture content(7%). Low amount composition of caco3 and starch have high bulk density of chalk is obtained but its amount is high the bulk density is low. The optimum values obtained were bulk density (1.135g/cm3), caco3 (30gm) and starch (10 gm.). The plant is economically feasible that its rate of return 33.94% which is greater than 12% and its initial investment cost will be recovered fully within only 2years and 4 months , which makes the plant is viable. | en_US |
| dc.language.iso | en_US | en_US |
| dc.subject | Chemical and Food Engineering | en_US |
| dc.title | Production of dustless Chalk | en_US |
| dc.type | Thesis | en_US |
