Hazardous jarosite use in developing non-hazardous product for engineering application

Area of Science:

• Environmental Science
• Materials Science
• Waste Management

Background:

• Jarosite, a hazardous byproduct of zinc metal extraction, poses significant global disposal challenges.
• Jarosite contains higher concentrations of toxic elements (lead, zinc, sulfur, cadmium, chromium, copper) and radionuclides compared to coal combustion residuals (CCRs) and soil.
• The fine texture of jarosite contributes to its high surface area, porosity, and water-holding capacity.

Purpose of the Study:

• To immobilize and recycle hazardous jarosite waste from the Hindustan Zinc Limited, India.
• To investigate the potential of using CCRs (fly ash) and clay soil for jarosite stabilization.
• To assess the environmental compliance and engineering suitability of the developed jarosite-based products.

Main Methods:

• Jarosite was mixed with CCRs and clay soil in various ratios.
• Solidified/stabilized (s/s) sintered jarosite-CCRs products were created.
• Compressive strength, water absorption, and toxic element leaching (USEPA-TCLP) were evaluated.

Main Results:

• Jarosite particles are finer than CCRs, exhibiting higher porosity and surface area.
• Jarosite bricks with a 3:1 jarosite-clay ratio achieved high compressive strength (140 kg/cm²) but exceeded TCLP limits for toxic elements.
• A 2:1 jarosite-clay ratio with 15% CCRs resulted in s/s-sintered products that comply with USEPA-TCLP limits and are suitable for engineering applications.

Conclusions:

• Jarosite can be effectively immobilized and recycled into construction materials.
• The combination of jarosite, clay, and CCRs offers a viable solution for managing hazardous jarosite waste.
• The developed s/s-sintered products meet stringent environmental leaching standards and engineering requirements.