Annaka Refinery of Toho Zinc Company Limited, located 100km to northwest of Tokyo, has the annual production capacity of about 140,000tons of electrolytic zinc. On the other hand Onahama Refinery, located 200km to northeast of Tokyo, has the fluosolid roaster which treats 500ton per day of zinc concentrate and produces 570tons of sulfuric acid. Onahama plant provides about 150,0000tons zinc calcine per year for Annaka plant.
This paper describes significant improvements and achieved results at the both Refineries during the last decade.
