MODELING AND OPTIMIZATION OF RARE EARTH MINERAL FLOTATION USING
SALICYLHYDROXAMIC ACID
Authors: Richard LaDouceur1, Avimanyu Das2, Courtney A. Young3, Peter A. Amelunxen4
1
rladouceur@mtech.edu, Montana Tech, Metallurgical and Materials Engineering, 1300 W. Park St. Butte, MT
59701 +1 (406) 491-4012
2
adas@mtech.edu, Montana Tech, Metallurgical and Materials Engineering, 1300 W. Park St. Butte, MT 59701 +1
(406) 496-4794
3
cyoung@mtech.edu, Montana Tech, Metallurgical and Materials Engineering, 1300 W. Park St. Butte, MT 59701
+1 (406) 496-4158
4
peter@aminpro.com, Aminpro Peru, Av Luis Carranza 1921, Lima, Peru +51 (1) 425-3756
KEYWORDS: Flotation, rare earth minerals, modeling, salicylhydroxamic acid collector
ABSTRACT
Many of the rare earth elements, the lanthanide series on the periodic table, are on the U.S. Department of Defense
Strategic and Critical Materials list. In this regard, the U.S. Army Research Laboratory (ARL) has funded several projects
at Montana Tech focusing on rare earth element recovery from natural resources. Current froth flotation operations utilize
n-octyl hydroxamate for rare earth mineral extraction; however, recovery is not ideal and flotation performance can be
improved. Salicylhydroxamic acid (C7H7NO3) was identified as a novel collector due to similarities with n-octyl
hydroxamate, notably the amine head group. Salicylhydroxamic acid is primarily used in the medical industry with the
head group being ideally suited as a collector for rare earth minerals.
Figure 1: Ball and Stick Model of Salicylhydroxamic Acid
Parametric studies were performed for the flotation of rare earth minerals by modifying a wide range of variables.
Mechanical variables of a 6L bench scale flotation cell, such as air inlet flow, rotor speed, and milling time were modified
to elucidate energy input parameters for the desired minerals. Chemical parameters such as collector concentration and pH
were varied to understand solution chemistry considerations of the salicylhydroxamic-rare earth mineral system. The study
obtained a statistically significant experimental model for the flotation of rare earth minerals. A two-stage, compartmental
model was also utilized for the determination of the first-order flotation rate constants for each mineral. Optimized recovery
of rare earth minerals was found to occur at near neutral pH ranges using salicylhydroxamic acid with maximum recoveries
approaching ideal industrial standards.
Figure 2: Predictive 3-D contour plot for recovery of rare earth minerals as determined with Design Expert.