The role of additives in improving the flammability and calorific value of leather shavings and the binding of chromium compounds in ash.

• Leather shavings do not allow for autothermal combustion when combusted directly. • Adding wood biomass to tannery waste results in a complete combustion of such mixture. • Lower quality pellets combustion results in a prominent afterburn. • Large percentage of additive leads to ash sintering, smaller additions result in fine ash. • The ash from wet blue tannery waste combustion traps large amounts of Cr 2 O 3. Leather processing companies are struggling with the problem of increasing costs of post-production waste disposal. Therefore, the issue of thermal waste disposal at the plant and the use of generated heat in the production process is becoming more and more popular. Leather waste on its own does not allow for autothermal combustion despite the sufficient higher heating value (HHV). Therefore the Authors proposed to improve the flammability of the fuel by adding a small amount of wood sawdust to leather waste and produce premixed pellets. Six such samples were incinerated in a laboratory-scale reactor, which enables the simultaneous measurement of characteristic temperatures, exhaust gas analysis and sample mass loss rate. Research has shown that even a small addition of sawdust enables a stable combustion process and does not cause the formation of sinters. In addition, studies of the ash showed that in the case of chromium-containing waste, a large part of it remained in the ash in the form of Cr 2 O 3. Nevertheless, very fine ash causes the small fraction chromium to be carried with the flue gas stream, therefore controlled agglomeration of the ash structure would be advisable in the final installation. Emission analysis showed high and moderately high NO x and SO 2 emissions, decreasing with the increase in the amount of sawdust addition in the sample. Research has shown that leather waste is not a burden, but can be an attractive and safe source of energy for the company, while improving waste management in a circular economy. [ABSTRACT FROM AUTHOR]