This study examined roasting cinnabar ore, which contains mercury, at temperatures between 300-600°C with and without the addition of CaO. Thermodynamic modeling and kinetic experiments were performed. Without CaO, the maximum weight loss of ore was 32.72% at 300°C for 60 minutes and 90.96% at 600°C for 15 minutes. With CaO, the maximum weight loss was reached faster at 69.46% for 30 minutes at 500°C. Kinetic analysis showed the roasting was controlled by chemical reaction rates. A mathematical model was developed to predict weight loss based on temperature and time. Higher temperatures were found to be important for effective cinnabar ore roasting.

1. STUDY OF CINNABAR ORE ROASTING AT TEMPERATURE 300-
600O
C WITH AND WITHOUT CaO ADDITION
Agastya Prastita Mahendradhany, Zulfiadi Zulhan
Department of Metallurgical Engineering, Institut Teknologi Bandung
ACKNOWLEDGEMENTS. Ir. Wiku Padmonobo as Metallurgical Manager of PT.
Geoservices (Ltd). and Dr. Ing. Zulfiadi Zulhan as Head of Pyro-metallurgy Laboratory. This
work was conducted by PT. Geoservices Ltd. and funded by Department of Metallurgical
Engineering.
Abstract
The usage of mercury in human life has begun from hundreds to thousands years ago.
Mercury has many uses, especially as a component in measuring instruments and sensors,
batteries, bulbs, fuses, gold amalgamation, and catalyst in the chemical industry. Recent
research has shown the potential of mercury as a component of superconductor because of its
excellent superconductivity properties. Indonesia has the potential for cinnabar mines that
containing HgS over 70%. Thermodynamics and kinetics study are performed on cinnabar ore
roasting which it can be the first step in harnessing the potential of cinnabar mineral processing
in Indonesia.
This study started by predicting the process using FactSage, a process simulation
software, and delivering some process simulation results. The chemical composition and
mineral contained in cinnabar ore were predicted by XRF and XRD. TG/DTA analysis was
performed to observe the weight loss trend during heating. Roasting experiments were carried
out at temperature 300 – 600o
C with time variations from 2 to 60 minutes and with the addition
of CaO at 300 to 600o
C in 30 minutes. The flue gas then quenched into a solution of 3% H2O2
and titrated to determine the sulphur recovery.
The experimental result showed that weight loss increased over time and temperature.
In cinnabar ore roasting without CaO addition at 300o
C for 60 minutes, the weight loss was
32.72%. However, at 600o
C for 15 minutes, the weight loss reached its maximum value of
90.96%. In comparison, with CaO addition, the weight loss reached its maximum value of
69.46% for only 30 minutes at 500o
C. Using kinetics study, it showed that cinnabar ore roasting
was controlled by chemical reaction rate mechanism. Using statistical method and binary
logistic regression equation for probability, a mathematical model for cinnabar ore roasting
was expressed by ! =#
$%&(()*.),-.*.*)-/.*.*01)
$%& ()*.),-.*.*)-/.*.*01 .)
where X is the weight reduction (%), T is
temperature (o
C) and t is time (minute). It was also shown that the temperature plays an
important role for cinnabar ore roasting.
Keywords: cinnabar ore roasting, mathematical model, thermodynamic, kinetics, factsage.