Removal of Iron Impurity from Vein Quartz by Acid Leaching
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Date
2018
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Journal ISSN
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Publisher
Uva Wellassa University of Sri Lanka
Abstract
Vein quartz is the major source of silicon for manufacturing of solar cells, computer
chips, and silicon carbide. Nevertheless, high-tech applications of vein quartz do not
apply in industries due to iron impurities that is the major problem in the quartz
processing industries in Sri Lanka. The aim of the investigation was to enhance the
purity of exporting semi processed vein quartz by acid leaching. Particle size
reduction processes crushing, grinding and milling increase the amount of iron in
the quartz and this secondary iron concentration needs to be removed to produce
more purified quartz. Thus, in this research quartz was obtained using raw quartz
near Badulla area. Raw quartz was processed using primary and secondary crushers
and then it was separated into four size fractions (125 rtm, 500 rim, 1 mm, and 8
mm). The acid leaching was employed for iron removal. Atomic Absorption
Spectrophotometer (AAS) was used to measure iron content before and after the
leaching. As preliminary studies, Hydrochloric acid and Nitric acids were employed
for the leaching and Liquid-Solid ratio was 5:1. According to the results which were
observed as preliminary study, HCl was chosen for the leaching and effect of the
HC1 for the removal of iron was examined. The particle size of the quartz, leaching
time, concentration of the reagents were used as parameters. Leaching was done
under normal atmospheric conditions (25 °C, 1 atm). The acid leaching of vein
quartz resulted in a reduction of 60 — 65% Iron from the original natural state. Since
iron dissolution is a photochemical reaction experiment was conducted in controlled
conditions (250 — 500 lux). A progressive amount of leaching (60 — 65%) of iron
from quartz was obtained under following conditions, a higher concentration of HC1
(5M), smallest size fraction (0-125 rtm), and 60 hrs. leaching time. Under these
conditions, a higher purity of quartz powder can be achieved.
Key Words: Quartz, Leaching, Quartz impurity removal
Description
Keywords
Materials Sciences, Mineral Sciences