M. Nagamori et Ja. Boivin, Technico-economic simulation for the HCl-leaching of hybrid serpentine andmagnesite feeds, CAN METAL Q, 40(1), 2001, pp. 47-60
A flexible technico-economic computer model was developed to minimize the o
perating cost of the HCl-leach of mixed feeds consisting of serpentine and
magnesite ores in a magnesium electrolytic reduction plant. A complete mass
balance was first established for HCl-leaching and filter cake washing by
taking into account such process variables as the extent of MgO extraction
from serpentine ore, pulp density of leach slurry, MgCl2 concentration of f
iltrate, moisture content of filter cake and degree of cake washing by disp
lacement and diffusion mechanisms. A mathematical model was then built by c
ombining the mass balance with the costs of serpentine ore preparation, fil
tration, brine evaporation and waste wet cake disposal as well as the price
s of magnesite ore, hydrochloric acid and electricity. The model includes t
he capital and operating costs of hydrometallurgical processing from ore pr
eparation to the production of magnesium chloride hexahydrate MgCl2. 6H(2)O
. The technico-economic simulation model shows that when the respective cos
ts of serpentine and magnesite ores are $15/t and $90/t, the lowest product
ion cost of hexahydrate can be achieved with a leach-feed of about 65% serp
entine and 35 % magnesite, and by washing the filter-cake with hot water ha
ving a volume 1.3 times that of the occluded brine.