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The Recovery of Critical Minerals from Pegmatite Dykes
Damian Connelly
METS Engineering Group, Perth
ABSTRACT: Pegmatite dykes are not uncommon in a number of areas around the world. However, pegmatitic
dyke deposits of critical metals such as lithium, tin, tantalum, beryllium and niobium are less common but
becoming increasingly significant. In some cases, other rare earth elements have been identified in the pegmatite
dykes. The lithium bearing polymetallic pegmatite ore is commonly known as LPPO. The halo geochemistry
reflects the internal evolution of the crystallizing pegmatite system, with residual fluid rich in incompatible
elements accumulated by geochemical fractionation (Be, B, Cs, Sn, Ta) and by auto-metasomatic resorption
of spodumene and K-feldspar (Li, Rb). The potential to exploit these deposits for their critical minerals is very
attractive. Historically tin and tantalum were recovered and some current lithium miners produce tantalum as
a by-product usually with low metal recoveries.
Lithium-caesium-tantalum pegmatite ore-processing methods depend on the minerals being processed and the
desired end product grade. Different lithium end uses require different degrees of processing of silicate ores.
Large-scale mining operations employ crushing, grinding, and gravity separation techniques to refine the ore
and prepare concentrates for further processing by roasting, smelting or hydrometallurgy. Tantalum is recover-
able by gravity but separation from niobium is difficult due to the similar chemistry. Virtually all of the caesium
is currently recovered from pegmatites by means of acid digestion.
Recent efforts to test these ores and recover lithium, tantalum, beryllium, and niobium has proven difficult
because the mineralogy is complex and a combination of gravity, dense media (DMS), flotation and hydro-
metallurgical techniques are required to achieve satisfactory recoveries. Being poly metallic and with very high
individual metal prices, the ores are very attractive. This paper describes the testwork and efforts to develop a
viable flowsheet for some of these ores.
INTRODUCTION
Whilst there has been significant growth in hard rock lith-
ium mining and production, lithium conversion extraction
technology to produce battery grade lithium hydroxide or
carbonate is now mature. As more exploration has been
undertaken, it is now clear that all lithium bearing pegma-
tite dykes are not the same, with some containing princi-
pally lithium and some dykes also contain significant levels
of tin, tantalum, niobium, caesium and beryllium. These
recently discovered occurrence of significant LPPO depos-
its, however, will challenge how these ores are processed to
recover beryllium, tantalum, niobium and tin as well as
lithium. The mineralogy is complex and there is very little
technical knowledge in the literature most of the infor-
mation relate only to lithium. Pilbara Minerals recovers
a tantalum by product by gravity. Talison at Greenbushes
recovered tantalum and tin by selective mining from the
lithium ore body. The focus of this paper is the more
The Recovery of Critical Minerals from Pegmatite Dykes
Damian Connelly
METS Engineering Group, Perth
ABSTRACT: Pegmatite dykes are not uncommon in a number of areas around the world. However, pegmatitic
dyke deposits of critical metals such as lithium, tin, tantalum, beryllium and niobium are less common but
becoming increasingly significant. In some cases, other rare earth elements have been identified in the pegmatite
dykes. The lithium bearing polymetallic pegmatite ore is commonly known as LPPO. The halo geochemistry
reflects the internal evolution of the crystallizing pegmatite system, with residual fluid rich in incompatible
elements accumulated by geochemical fractionation (Be, B, Cs, Sn, Ta) and by auto-metasomatic resorption
of spodumene and K-feldspar (Li, Rb). The potential to exploit these deposits for their critical minerals is very
attractive. Historically tin and tantalum were recovered and some current lithium miners produce tantalum as
a by-product usually with low metal recoveries.
Lithium-caesium-tantalum pegmatite ore-processing methods depend on the minerals being processed and the
desired end product grade. Different lithium end uses require different degrees of processing of silicate ores.
Large-scale mining operations employ crushing, grinding, and gravity separation techniques to refine the ore
and prepare concentrates for further processing by roasting, smelting or hydrometallurgy. Tantalum is recover-
able by gravity but separation from niobium is difficult due to the similar chemistry. Virtually all of the caesium
is currently recovered from pegmatites by means of acid digestion.
Recent efforts to test these ores and recover lithium, tantalum, beryllium, and niobium has proven difficult
because the mineralogy is complex and a combination of gravity, dense media (DMS), flotation and hydro-
metallurgical techniques are required to achieve satisfactory recoveries. Being poly metallic and with very high
individual metal prices, the ores are very attractive. This paper describes the testwork and efforts to develop a
viable flowsheet for some of these ores.
INTRODUCTION
Whilst there has been significant growth in hard rock lith-
ium mining and production, lithium conversion extraction
technology to produce battery grade lithium hydroxide or
carbonate is now mature. As more exploration has been
undertaken, it is now clear that all lithium bearing pegma-
tite dykes are not the same, with some containing princi-
pally lithium and some dykes also contain significant levels
of tin, tantalum, niobium, caesium and beryllium. These
recently discovered occurrence of significant LPPO depos-
its, however, will challenge how these ores are processed to
recover beryllium, tantalum, niobium and tin as well as
lithium. The mineralogy is complex and there is very little
technical knowledge in the literature most of the infor-
mation relate only to lithium. Pilbara Minerals recovers
a tantalum by product by gravity. Talison at Greenbushes
recovered tantalum and tin by selective mining from the
lithium ore body. The focus of this paper is the more