Recovered polyvinyl alcohol as an alternative binder for the production of metallurgical quality coke breeze briquettes

Coke breeze briquettes are promising low-cost substitute to metallurgical coke, prepared by adding binder to the coke breeze to form briquettes. At present, pregelatinized starch is used as binder in the preparation of briquettes, but its food and confectionary applications restrict its usage on account of high cost and ease of availability. Subsequently, there is a necessity to develop alternative binders for the briquetting process, without affecting the briquette properties. Polyvinyl alcohol (PVA) could be one such possible binder. The textile industry generates waste streams with significant amounts of PVA that can be recovered by membrane filtration. The present work, therefore investigates the possibility of using pure polyvinyl alcohol (pPVA), recovered polyvinyl alcohol (rPVA), and mixtures of rPVA with pregelatinized starch as binders for coke breeze briquetting. Weak green briquettes were produced by rPVA binder. The quality of briquettes improved after addition of pregelatinized starch to rPVA and this was found to be equivalent to pure polyvinyl alcohol (pPVA) binder briquettes. The mixed (rPVA+ Pregelatinized starch) binder produced briquettes with UC strength 1347 kPa. The study demonstrates the fact that good quality briquettes can be formed by rPVA when used in combination with minimal quantities of pregelatinized starch.