Some info on HPA - High Purity AluminaHPA is a...

Some info on HPA - High Purity Alumina

HPA is a high-valuematerial needed for lithium-ion battery components and synthetic sapphire usedin LED lights, semiconductor wafers and scratch-resistant smartphone glass.

Production of Alumina from kaolin by acid leach • Process researched by USGS in 1945-46, but shelved as the smelting of alumina produced from bauxite was much cheaper then • Kaolin is calcined to produce meta kaolin • Leach meta kaolin in hydrochloric acid producing ACH • Precipitate ACH from saturated solution by bubbling gaseous Chlorine through the solution • Wash the ACH precipitate several times to remove impurities • Calcine the ACH to remove the water and Chlorine – recover the Chlorine gas • Result is HPA

https://ausimm.com/wp-content/uploads/2019/08/03-Hill-End-Gold-Kaolin-24-May2018-AusIMM.pdf

• HPA is a very pure form of aluminium oxide

ie, >99.99% pure, it has <100 ppm of

impurities. This is known as 4N HPA.

• 5N or 99.999% HPA is increasingly in demand

for high performance technology. It contains

<10 ppm impurities.

• HPA is chemically inert in most environments,

has a very high melting point, doesn’t conduct

electricity, is a good conductor of heat, and is

very abrasive.

• HPA’s properties make it desirable for high-growth industries

such as lithium batteries and photonic technologies

• When HPA is grown into Synthetic Sapphire crystal it is used

in:

• LED light / Semiconductor substrates

• Phosphors / Diodes

• Lasers

• Optical lenses

• HPA adds significant performance and safety characteristics

demand for HPA

when used in lithium battery separators

• New applications are forecast to extend the growing

Demand for HPA has risen eight-fold since 2003

and is forecast to triple by 2030

• LEDs consume more than half the annual HPA

production and is growing strongly. LED’s

currently have ~20% of the lighting market

with saturation expected above 80%.

• Lithium batteries are an emerging HPA market

and forecast to grow strongly as batteries

penetrate the auto and power storage markets

• Additional demand includes medical, optical,

smart phone screens, watch glass and bullet

proof windows

The largest use of HPA is to make synthetic

sapphire. Properties of Synthetic Sapphire

• Extreme hardness (2nd only to diamonds on the

Mohs scale)

• Transmits in UV, visible and IR wavelengths

• High heat resistance and excellent thermal

conductivity

• High electrical resistance

• Chemically inert and insoluble (biocompatible)

• Lithium batteries have been known to catch fire;

Coating the separator in HPA addresses this issue.

This market is forecast to grow strongly.

• The high melting point of HPA provides greater

thermal stability to the battery, improving safety

• HPA is a good electrical insulator while allowing ions

to flow freely

• HPA significantly improves impedance (Macmullan

number <3) allowing for high power capability and

low temperature performance

• HPA filled separators improve battery life cycle and

lower self-discharge

• 4N HPA currently sells for US$25-35,000/t 2017 prices

• 5N HPA sells for US$50-60,000/t

• Smelter grade 98.5% Alumina sells for circa US$400/t

• HPA prices are forecast to remain strong with new

demand growth matching or exceeding supply

growth.

• Quality challenges will constrain supply growth