Development of a value-added soil conditioner from high shear co-granulation of organic waste and limestone powder

• Granules were successfully produced from binary mixtures of limestone and tea waste.
• Density of binary mixture granules can be estimated from density of components.
• Tablet and granule strength decrease with an increase in tea waste composition.

This paper reports on a technical feasibility study of the production of organo-mineral fertiliser from the co-granulation of limestone powders with tea waste. The results from this preliminary study show that the co-granulation of tea waste provided an alternative method of waste recovery, as it converts the waste into a value-added product. Fertiliser granules were successfully produced from various compositions of limestone and tea waste. The effect of tea waste concentration on granule strength was analysed; the granule strength was in the range 0.2 to 1.8 MPa depending on powder composition; increasing the tea waste mass fraction resulted in a reduction in granule strength. Varying the tea waste to limestone ratio also influenced the compressibility of the granules; the granules compressibility increased with increasing tea waste mass fraction. It was further found that increasing the mass fraction of tea waste in the binary mixture of powder reduced the granule median size of the batch.

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