1351
Process Intensification for Rare Earth Elements Adsorption by
Resonant Vibratory Mixing
Oluwatosin Adebayo, Zainab Nasrullah, Richard Ladouceur
Department of Metallurgical and Materials Engineering, Montana Technological University, Butte, Montana
ABSTRACT: The adsorption capacity of biochar from hemp feedstock for six rare earth elements (lanthanum,
terbium, neodymium, dysprosium, praseodymium, and holmium) was investigated. An innovative approach
to enhancing the adsorption of rare earth elements using biochar was studied and investigates the potential of
resonant vibratory mixing (RVM) as a process intensification method compared to conventional mechanical
mixing for the adsorption process. Hemp hurds as source of biomass was pyrolyzed to produce biochar at a
temperature of 450°C for 60 minutes. The prepared biochar was characterized by FTIR (Fourier Transform
Infra-red), SEM (Scanning Electron Microscopy), Surpass 3 Electrokinetic solid surface analyzer, and BET
(Brunauer-Emmett-Teller). Five different concentrations of each rare earth element were prepared by dissolving
known amount of the rare earth chlorides in di-ionized water. Rare earth ore samples obtained from Bear Lodge
deposits in Wyoming were also leached using 0.3M concentration of oxalic acid to produce REE leachates
of pH 1, 4, and 7 respectively. An experimental design was set up for the adsorption experiments with three
variables which are time of mixing, intensity of vibration, and adsorbent dosage (mass). The results indicated
that RVM as a novel mixing method greatly influence the adsorption of REEs from aqueous solutions and it
serves as a faster intensification method due to its influence on high recovery rate even at short mixing time.
Keywords: Intensification, Biochar, Resonant Vibratory Mixing, Rare Earth Elements, Adsorption, Experimental
Design.
INTRODUCTION
Rare earth elements also referred to as “REEs” or “critical
elements” are group of 17 metallic elements on the periodic
table comprising of 15 lanthanides in addition to Yttrium
and scandium, as established by the international Union of
Pure and Applied Chemistry (IUPAC).
In recent times, especially the beginning of the 20th
century, REEs have received a lot of attention from the
high-tech industry and defense department of developed
countries around the world. There are copious proportions
of rare earth elements across the world, but ores that are
rich in REEs exists in dispersed distribution which makes
it difficult to find them in economically viable quantities
(Kang and Kang 2020). The importance of REEs to recent
technological advancement cannot be over-emphasized
and this is due to the special properties possessed by REEs
(Barrett and Dhesi 2001). The major characteristics like
chemical, metallurgical, optical, and magnetic make REEs
extremely desirable by consumer electronics, defense, clean
energy, aerospace, and metal manufacturing industries.
Since the beginning of the early 2000s, transition properties
of REEs ions have been investigated by the academic com-
munity and the optical equipment manufacturers. Some of
the uses of rare earth elements are illustrated in Figure 1.
Process Intensification for Rare Earth Elements Adsorption by
Resonant Vibratory Mixing
Oluwatosin Adebayo, Zainab Nasrullah, Richard Ladouceur
Department of Metallurgical and Materials Engineering, Montana Technological University, Butte, Montana
ABSTRACT: The adsorption capacity of biochar from hemp feedstock for six rare earth elements (lanthanum,
terbium, neodymium, dysprosium, praseodymium, and holmium) was investigated. An innovative approach
to enhancing the adsorption of rare earth elements using biochar was studied and investigates the potential of
resonant vibratory mixing (RVM) as a process intensification method compared to conventional mechanical
mixing for the adsorption process. Hemp hurds as source of biomass was pyrolyzed to produce biochar at a
temperature of 450°C for 60 minutes. The prepared biochar was characterized by FTIR (Fourier Transform
Infra-red), SEM (Scanning Electron Microscopy), Surpass 3 Electrokinetic solid surface analyzer, and BET
(Brunauer-Emmett-Teller). Five different concentrations of each rare earth element were prepared by dissolving
known amount of the rare earth chlorides in di-ionized water. Rare earth ore samples obtained from Bear Lodge
deposits in Wyoming were also leached using 0.3M concentration of oxalic acid to produce REE leachates
of pH 1, 4, and 7 respectively. An experimental design was set up for the adsorption experiments with three
variables which are time of mixing, intensity of vibration, and adsorbent dosage (mass). The results indicated
that RVM as a novel mixing method greatly influence the adsorption of REEs from aqueous solutions and it
serves as a faster intensification method due to its influence on high recovery rate even at short mixing time.
Keywords: Intensification, Biochar, Resonant Vibratory Mixing, Rare Earth Elements, Adsorption, Experimental
Design.
INTRODUCTION
Rare earth elements also referred to as “REEs” or “critical
elements” are group of 17 metallic elements on the periodic
table comprising of 15 lanthanides in addition to Yttrium
and scandium, as established by the international Union of
Pure and Applied Chemistry (IUPAC).
In recent times, especially the beginning of the 20th
century, REEs have received a lot of attention from the
high-tech industry and defense department of developed
countries around the world. There are copious proportions
of rare earth elements across the world, but ores that are
rich in REEs exists in dispersed distribution which makes
it difficult to find them in economically viable quantities
(Kang and Kang 2020). The importance of REEs to recent
technological advancement cannot be over-emphasized
and this is due to the special properties possessed by REEs
(Barrett and Dhesi 2001). The major characteristics like
chemical, metallurgical, optical, and magnetic make REEs
extremely desirable by consumer electronics, defense, clean
energy, aerospace, and metal manufacturing industries.
Since the beginning of the early 2000s, transition properties
of REEs ions have been investigated by the academic com-
munity and the optical equipment manufacturers. Some of
the uses of rare earth elements are illustrated in Figure 1.