Zinc Recovery of Low Grade
Concentrate from Vazante Mine
by the Waelz Process
Fabiana M. Teixeira, Júlia M. Martins, Eder L. C. Martins, Pablo S. Pina,
Thiago O. N. Leite, Sérgio A. Penchel Jr. and Tone Takayama
Abstract Nexa Resources processes electric arc furnace dusts (EAFD) and other
sources of secondary zinc at its Juiz de Fora unit, mainly by the Waelz Process.
Aiming to increase the Waelz furnace feed, decrease stocks of the mines, and improve
the company’s recovery rate, a process to recover zinc from low grade concentrate
produced at the Vazante mine that are not suitable for the traditional Roast-LeachElectrowinning (RLE) process, due to the zinc content, were investigated in this
study. The zinc concentrates, containing around 18–20% of zinc, were tested in a
pilot scale Waelz furnace with the feed portion of 10 and 40% mixed with EAFD.
Another input with 100% of this material was also investigated, and all tests were
compared to the traditional feed of 100% EAFD. The parameters evaluated were
zinc recovery yield and accretion formation inside the furnace. Other parameters of
the furnace, such as reduction agent input, temperature, and residence time, were the
same as the industrial Waelz process. The proposed process showed good response
to accretion formation inside the furnace, such as with the increase in the portion of
the low grade concentrate in the feed, and the accretions formation decreased. The
technique was also efficient to zinc recovery yield with the feed portion of 10, 20,
and 40% resulting around 92% of recovery. However, for the test feeding only the
concentrate, the zinc recovery yield was decreased to 82%.
Keywords Base metals recovery · Low grade concentrates · Waelz process · Zinc
Introduction
The Waelz process is the most used route in the world for the treatment of electric
arc furnace dust (EAFD) [1]. It is a pyrometallurgical process characterized by the
volatilization of metals like zinc, cadmium, and lead in a rotary kiln from a solid
mixture by means of reduction by coal or other reduction agent, generating a solid
F. M. Teixeira (B) · J. M. Martins · E. L. C. Martins · P. S. Pina · T. O. N. Leite ·
S. A. Penchel Jr. · T. Takayama
Nexa Resources, Br 267, Km 119, Igrejinha, Juiz de Fora, Brazil
e-mail: fabiana.teixeira@nexaresources.com
© 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_18
231
Concentrate from Vazante Mine
by the Waelz Process
Fabiana M. Teixeira, Júlia M. Martins, Eder L. C. Martins, Pablo S. Pina,
Thiago O. N. Leite, Sérgio A. Penchel Jr. and Tone Takayama
Abstract Nexa Resources processes electric arc furnace dusts (EAFD) and other
sources of secondary zinc at its Juiz de Fora unit, mainly by the Waelz Process.
Aiming to increase the Waelz furnace feed, decrease stocks of the mines, and improve
the company’s recovery rate, a process to recover zinc from low grade concentrate
produced at the Vazante mine that are not suitable for the traditional Roast-LeachElectrowinning (RLE) process, due to the zinc content, were investigated in this
study. The zinc concentrates, containing around 18–20% of zinc, were tested in a
pilot scale Waelz furnace with the feed portion of 10 and 40% mixed with EAFD.
Another input with 100% of this material was also investigated, and all tests were
compared to the traditional feed of 100% EAFD. The parameters evaluated were
zinc recovery yield and accretion formation inside the furnace. Other parameters of
the furnace, such as reduction agent input, temperature, and residence time, were the
same as the industrial Waelz process. The proposed process showed good response
to accretion formation inside the furnace, such as with the increase in the portion of
the low grade concentrate in the feed, and the accretions formation decreased. The
technique was also efficient to zinc recovery yield with the feed portion of 10, 20,
and 40% resulting around 92% of recovery. However, for the test feeding only the
concentrate, the zinc recovery yield was decreased to 82%.
Keywords Base metals recovery · Low grade concentrates · Waelz process · Zinc
Introduction
The Waelz process is the most used route in the world for the treatment of electric
arc furnace dust (EAFD) [1]. It is a pyrometallurgical process characterized by the
volatilization of metals like zinc, cadmium, and lead in a rotary kiln from a solid
mixture by means of reduction by coal or other reduction agent, generating a solid
F. M. Teixeira (B) · J. M. Martins · E. L. C. Martins · P. S. Pina · T. O. N. Leite ·
S. A. Penchel Jr. · T. Takayama
Nexa Resources, Br 267, Km 119, Igrejinha, Juiz de Fora, Brazil
e-mail: fabiana.teixeira@nexaresources.com
© 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_18
231