Processing of Black Board Chalk from Pachymelania Aurita and Lanister Variscus Shells

A mixture of marble dust and periwinkle shells (achymelania Aurita) and a mixture of marble dust and snail (LanisterVariscus) shells were used to replace the conventional calcium carbonate (CaCO3) used for the production of classroom chalk. The bulk density for the crushed periwinkle shells and crushed snail shells at a particle size of ≤63μm were 1.14g/ml and 1.12 g/ml respectively. From the results obtained from the complexometric titration, the percentage composition of calcium carbonate (CaCO3) content in crushed periwinkle shells and crushed snail shells were 85.06% wt. and 85.91% wt. respectively. The quality of chalk produced from the mixture of marble dust (MD) and crushed periwinkle shells (CPS) at at a ratio of 1:3 was high with a breaking strength of 56.4 kg/cm2. The result from the mixture of marble dust (MD) and crushed snail shells (CSS) at a ratio of 1:3 was also high with a breaking strength of 54.7 kg/cm2 . The results obtained show that the mixture of marble dust and crushed periwinkle shells at ratio of 1:3 and a mixture of marble dust and crushed snail shells at a ratio of 1:3 could replace the conventional calcium carbonate for classroom chalk production. Key words: PachymelaniaAurita, LanisterVariscus, complexometric, marble dust, snail, periwinkle shells, marble dust