Publication: Mechanism and kinetic reactions of malaysian ilmenite from terengganu in a hydrochloric acid leaching system
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Date
2023-07-01
Authors
Siti Asmidar Binti Ibrahim
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Abstract
The potential of ilmenite sand from Sungai Cheniah, Bukit Kelip, Terengganu,
Malaysia to produce synthetic rutile through a reductive leaching method that uses
hydrochloric acid as a leaching reagent and iron as a reducing agent is studied. Since
inadequate information regards ilmenite deposited at this catchment area, it is critical
to investigate the properties of the ilmenite that used in this study which can shed light
on the behaviour of ilmenite during the leaching process. Based on the characterization
analyses, the ilmenite sand, IS is classified as low grade since the TiO2 content is
41.53% right after the pre-treatment process conducted and were used as the feedstock
for the leaching process. It is also having wide span value meaning that its h has a wide
size fraction of unidentical size particles. Therefore, the liberation study was executed
and (+53-63) µm size fraction was selected to be the input of the leaching study as it
consists of the highest liberated particles compare to other size fraction.
As to determine the optimum conditions of the reductive leaching process for
ilmenite, parameters such as concentration of hydrochloric acid (HCI), acid-to-solid
ratio, temperature, and concentration of reducing agent was studied using design of
experiment (DOE). The result of the leaching process was assessed using analysis of
variance (ANOVA) and optimal criteria were pointed out to be 9M HCl, 90°C, 0.4g/g
of iron powder, and 4g/L solid liquid ratio. The maximum recovery is 96.42% Fe and
97.24% Ti. By developing this analysis statistically which is based on the mathematical models, it could be useful for predicting and comprehending the effects
of experimental conditions.
To elucidate the reaction kinetics and mechanism of ilmenite leaching in HCl
solution, only HCl concentration and temperature were considered as the factors for
leaching study. Based on Fe-Ti correlation for both factors, it shows that the Fe
dissolved two-time folds compared to Ti dissolution. This direct leaching of ilmenite
particles obeyed a shrinking core kinetic model, supporting the view that the proton
diffusion through a product layer is the rate-controlling step. This can be supported by
the activation energy values obtained for both 32.3 kJ/mol Fe and 30.2kJ/mol Ti which
is below 40 kJ/mol which indicates the diffusion control rate.