S. Simukanga et Wc. Lombe, ELECTROCHEMICAL PROPERTIES OF APATITE AND OTHER MINERALS OF ZAMBIAN PHOSPHATE ORES IN AQUEOUS-SOLUTION, Fertilizer research, 41(2), 1995, pp. 159-166
A microelectrophoresis technique was used to study the electrochemical
properties of apatite, quartz and hornblende from Chilembwe phosphate
ore;and apatite, calcite and magnetite from Kaluwe phosphate ore. The
tests were conducted in distilled water and the water near the source
of the phosphate ores under study. The apatite from Chilembwe gave an
isoelectric point (i.e.p.) value of pH 6 in distilled water while in
Mankwala Dam water the i.e.p. was of pH 4. Quartz and hornblende were
negatively charged throughout the entire pH range studied in both case
s. Apatite from Kaluwe showed an i.e.p. value of pH 3.8 while calcite
and magnetite had i.e.p. values of pH 6.1 and 4.1 in distilled water,
respectively However, in Kaluwe water the i.e.p. of calcite shifted to
pH 8.8 resulting in a charge reversal on either side of the i.e.p. Th
ere was no marked difference in the i.e.p. values of apatite and magne
tite in Kaluwe water from those in distilled water. Comparison of zeta
potential-curves for different apatites showed that they exhibit diff
erent i.e.p. values because of their variable composition.