Recycling hazardous jarosite waste using coal combustion residues

Increase in environmental concern due to improper management of both hazardous and non hazardous wastes released from different industrial process prioritized the necessity for the innovation research. In this context, this paper deals with the immobilization of jarosite waste released from the zinc industry and converting it into a value added product using coal combustion residues (CCRs) through solidification/stabilization (s/s) and sintering process. Experiments were conducted using different ratio of jarosite waste and clay soil with varying concentration of CCRs. The optimized experimental results (using jarosite waste and clay soil ratio of one with 15% CCRs) showed that it is possible to make a composite having desirable mechanical properties such as compressive strength (50–81 kg/cm2); water absorption (13–17%); shrinkage (11–32%); and density (1.6–1.8 gm cm−3) to use as a construction material. Under solid state sintering process, with the application of CCRs, the mineral phases such as X Fe3 (SO4)2(OH)6 [where X = K and NH4], 2Fe2O3SO3.5H2O, PbSO4, CaSO4 in jarosite waste were transformed into a silicate matrices. The leachate studies confirmed that the toxic elements such as Cd, Pb, etc. were immobilized in the jarosite waste composite and meeting the USEPA TCLP toxicity norms for safe utility. The composite product thus developed has showed potential for recycling jarosite waste in construction sector leading to cross sector waste recycling.

Research Highlights
► Jarosite waste is a hazardous waste.
► CCRs influenced to immobilize toxic substances in jarosite waste.
► Leachate of toxic elements in the jarosite composites were within USEPA TCLP norms.
► Characteristics of jarosite waste composites comply the standard for safe utility.