Start-up and Improvements of the New
Electrolysis Plant at Annaka Refinery
Takuhiro Yamaguchi
Abstract Annaka zinc refinery of Toho Zinc Co., Ltd. produces 100,000 tons of
electrolytic zinc per annum with its zinc content over 99.995%, using zinc concentrate as the main raw material. The zinc smelting process in Annaka refinery is the
hydrometallurgical method which consists of roasting, leaching, purification, and
electrowinning. The environment of zinc smelting business in Japan has been severer due to some operational cost increases. The high electric power price which
keeps rising after the Great East Japan Earthquake disaster in 2011 has still been the
biggest challenge. Under such circumstances, we renewed the obsolete No. 1 electrowinning plant which had operated for more than 70 years. This report describes
the improvement cost effect including the electricity power cost in Annaka refinery
and some improvements of the new plant in the start-up stage.
Keywords Zinc smelting process · Electrowinning process · Cooling tower control
Introduction
Overview of Annaka Zinc Refinery
Annaka refinery of Toho Zinc Co., Ltd. produces 100,000 tons of electrolytic zinc
per annum with a zinc content over 99.995%, using zinc concentrates as its raw
materials. As shown in Table 1, the production method of electrolytic zinc at Annaka
refinery is a hydrometallurgical method with a series of processing consisting of
roasting, leaching, purification, and electrowinning. An overview flow chart of the
process of Annaka refinery is shown in Fig. 1.
T. Yamaguchi (B)
Toho Zinc Co., Ltd. Annaka Refinery, 1443 Nakajuku, Annaka, Gunma 379-0197, Japan
e-mail: yamaguchi-takuhiro@toho-zinc.co.jp
© The Minerals, Metals & Materials Society 2020
A. Siegmund et al. (eds.), PbZn 2020: 9th International Symposium
on Lead and Zinc Processing, The Minerals, Metals & Materials Series,
https://doi.org/10.1007/978-3-030-37070-1_17
221
Electrolysis Plant at Annaka Refinery
Takuhiro Yamaguchi
Abstract Annaka zinc refinery of Toho Zinc Co., Ltd. produces 100,000 tons of
electrolytic zinc per annum with its zinc content over 99.995%, using zinc concentrate as the main raw material. The zinc smelting process in Annaka refinery is the
hydrometallurgical method which consists of roasting, leaching, purification, and
electrowinning. The environment of zinc smelting business in Japan has been severer due to some operational cost increases. The high electric power price which
keeps rising after the Great East Japan Earthquake disaster in 2011 has still been the
biggest challenge. Under such circumstances, we renewed the obsolete No. 1 electrowinning plant which had operated for more than 70 years. This report describes
the improvement cost effect including the electricity power cost in Annaka refinery
and some improvements of the new plant in the start-up stage.
Keywords Zinc smelting process · Electrowinning process · Cooling tower control
Introduction
Overview of Annaka Zinc Refinery
Annaka refinery of Toho Zinc Co., Ltd. produces 100,000 tons of electrolytic zinc
per annum with a zinc content over 99.995%, using zinc concentrates as its raw
materials. As shown in Table 1, the production method of electrolytic zinc at Annaka
refinery is a hydrometallurgical method with a series of processing consisting of
roasting, leaching, purification, and electrowinning. An overview flow chart of the
process of Annaka refinery is shown in Fig. 1.
T. Yamaguchi (B)
Toho Zinc Co., Ltd. Annaka Refinery, 1443 Nakajuku, Annaka, Gunma 379-0197, Japan
e-mail: yamaguchi-takuhiro@toho-zinc.co.jp
© The Minerals, Metals & Materials Society 2020
A. Siegmund et al. (eds.), PbZn 2020: 9th International Symposium
on Lead and Zinc Processing, The Minerals, Metals & Materials Series,
https://doi.org/10.1007/978-3-030-37070-1_17
221