A4 Conference proceedings

A Mechanistic Kinetic Model for Direct Zinc Pressure Leaching


Open Access publication

Publication Details
Authors: Zhukov Vladimir, Laari Arto, Koiranen Tuomas, Sharikov Yury
Publication year: 2017
Language: English
Title of parent publication: International Forum of Young Researchers "Topical Issues of Subsoil Usage"
JUFO level of this publication: 0
Permanent website address: http://old.spmi.ru/en#&panel1-1
Open Access: Open Access publication

Abstract


In the current study, a numerical
mechanistic kinetic model for direct leaching of zinc from iron containing
sphalerite concentrate is presented. The model is based on the well-known
shrinking-core model approach. However, in order to consider possible chemical
changes that might take place in the liquid phase the model is solved
numerically. This also makes it possible to separate and quantify different
factors that might limit the leaching process. It is suggested that the most
probable leaching mechanism is a combination of the acid attack and
electrochemical reaction mechanisms. At first, zinc sulphide reacts with
hydrogen ions at the surface of particles liberating zinc ions and forming
hydrogen sulphide. Then in the next step, hydrogen sulphide is oxidized by
ferric ions or molecular oxygen according to an electrochemical reaction
mechanism. The estimated reaction orders for the oxidants are close to 0.5
which supports the electrochemical mechanism. The mechanism of sphalerite
leaching also involves simultaneous surface reactions and internal diffusion of
oxidants. The obtained results show that the rate of the leaching process is
mainly limited by the surface reactions. However, internal diffusion might
decrease the leaching rate in some cases up to 50 % at higher sphalerite conversions.
It is also demonstrated in the study that new information can be obtained about
the kinetics of sphalerite leaching, the parameters affecting the leaching rate
and the uncertainties involved in the model predictions.


Research Areas

Last updated on 2017-01-11 at 10:00