Pure genius? How new technology could shake up HPA supply

By Cameron Perks
Published: Thursday, 26 January 2017

High purity alumina is typically produced via an add-on stage to traditional alumina extraction from bauxite, but at least two companies are on the cusp of breaking into the material’s supply chain with revolutionary new processing methods, Cameron Perks, IM Correspondent, finds.

LED lighting is expected to be an area of growth which will increase demand for high purity alumina. According to LED Lighting’s Global Outlook, demand is expected to reach 4.1bn lamps in 2025, from 864m lamps in 2015. 

High purity alumina (HPA), or aluminium oxide with a minimum purity of 99.99% (4N) Al2O3, is a high value speciality product with a broad range of uses. The material is most commonly turned into synthetic sapphire for use in LEDs, semiconductors, phosphors and lithium-ion (Li-ion) batteries, among other markets.

HPA is produced on an industrial scale via the Bayer refining or Hall-Heroult smelting techniques used to turn bauxite into alumina, followed by hydrolysis of aluminium alkoxide. Alternative methods are thermal decomposition and the water soluble/chlorine process.

Australia’s Altech Chemicals Ltd is attempting to shake up the HPA industry by producing the material directly from kaolin clay and is hoping to start commercial production next year.

Total HPA demand, according to Altech, was around 19,040 tonnes in 2014 – a figure which the company expects to grow rapidly. 

Altech estimates that continued expansion in the Li-ion battery market could see HPA consumption in this sector alone rise from around 1,000 tpa today to around 15,000 tpa by 2025. This forecast hinges on a recent bullish scenario prediction by Deutsche Bank that Li-ion battery usage will rise from 70 GWh/year in 2015 to 535GWh/year by 2025. 

The major application of HPA in Li-ion batteries is as a coating on the ceramic separator sheet that divides the cathode and anode electrodes within the battery (see Figure 1).

Figure 1: Structure of a Li-ion battery 
Source: Altech

HPA-coated separators improve battery safety by withstanding unusually high temperature incursions and reducing flammability during thermal runaway events. They also increase a battery’s discharge rate, lower self-discharge and lengthen battery life cycles. These advantages have prompted an increasing number of manufactures to use HPA in their batteries.

But while the Li-ion batteries show significant growth potential, it is the LED market which currently accounts for the largest share of HPA demand and this too is expected to require higher volumes in the near future.

If Altech’s demand estimates are correct, then the LED industry currently consumes just under 11,000 tpa HPA. Around 90% of LEDs use an HPA substrate, so higher LED usage will quickly boost HPA consumption. However, in this sector, HPA faces competition from silicon carbide and silicon metal substrates, which may reduce the pace of volume growth.

According to a 2017 Goldman Sachs report, entitled "The New Energy Landscape", LED technology’s share of the global lighting market is expanding and is slated to reach 43% this year, potentially rising to around 75% by 2020.

HPA end markets (%), 2015 
Source: Altech, 2016 
The HPA market opportunity
Orbite Technologies believes it has a system which can recycle red 
mud,  the waste product from traditional alumina production using the Bayer process. Red mud has increasingly become both an environmental and economic liability. it is also a highly caustic substance which contains "considerable" amounts of alumina, titanium and rare earths. According to Orbite, around 3bn tonnes of red mud are stored in ponds around the world with no viable alternative to re-use the material and 120m tpa is produced globally. In 2010 the collapse of MAL’s red mud tailings reservoir at the Ajka plant in Veszprem (pictured) left nine people dead. (Source: MAL).

In November 2016, Altech signed a 20-year lease agreement for a proposed HPA plant construction site in Johor, Malaysia where the company can take advantage of a corporate tax rate of just 25% to reduce its operating costs. The facility will produce around 4,000 tpa of 4N (see table) HPA – a product Altech expects to sell for around $23,000/tonne – from kaolin sourced from the company’s Meckering deposit in Western Australia. 

Meckering, which holds 1.22m tonnes of reserves and a further 11.5m tonnes in resources, only needs to be mined at a relatively slow rate according to Altech – around 42,055 tpa – owing to the alumia-rich nature of the ore, which averages 29.5% Al2O3 in the minus 300 micron kaolin fraction.

At the beginning of December last year, Altech submitted a proposal and a mine closure plan for Meckering which, if approved, will enable the company to start building the mine later this year. 

It expects to produce finished HPA at an all-in cash cost of approximately $8,140/tonne, yielding a gross cash margin of $14,860/tonne. At present, most HPA producers purchase aluminium sulphate or aluminium metal from which to produce HPA for around $3,000/tonne, before incurring their own processing costs. 

These economics, according to Altech, give the company a vertically integrated cost advantage on top of having a cheaper kaolin feedstock.

Using kaolin as an alternative alumina source to bauxite is not a new idea – there was significant research into this area in the US during the 1940s, spurred by the sinking of ships carrying bauxite imports during World War Two. 

One particularly well-known paper was published in 1946. Entitled the "Development of a Hydrochloric Acid Process for the Production of Alumina from Clay", it details the steps needed to extract alumina from kaolin, as well as the kaolin properties required for the mineral to be used as an alumina feedstock.

Altech’s process

Since every kaolin deposit is unique and Altech’s HPA production process has tailored the principles laid down in the 1946 paper to suit the Meckering ore. Meckering kaolin is first calcined at 600o C in an indirect rotary kiln, which converts the clay structure into a more reactive form. The material is then cooled, ball milled and screened to a particle size of less than 300 microns. 

The kaolin is leached with hydrochloric acid, converting all oxide components, with the exception of silica, to soluble chlorides. The resulting slurry is sent to a series of reactors where it is heated and condensed hydrochloric acid vapours are removed.

The leached slurry undergoes a series of filtration steps before it is crystallised and processed into a filter cake. The purified cake is then heated in stages to remove impurities, including any residual acid. The remaining product is a highly pure alpha-alumina, or HPA.

Figure 2: Altech’s proposed HPA chemical process flowsheet 
Source: Altech 

Once cooled, the HPA is fed into a grinding mill before being bagged, stored and dispatched. Altech’s modernised process allows the company to recapture and recycle the hydrochloric acid used to leach kaolin, bringing costs down compared to the original method.

The company’s modernised version of the standard alumina extraction process is shown in Figure 2.

Because the process of making HPA is well-known, Altech admits that there is a risk their production method will be copied, but has reassured its shareholders that it is "probably 5-6 years ahead" of any copycat competition.

Orbite Technologies

Although Altech is confident that it has a head start on anyone wishing to imitate its HPA process, there are other businesses that have been independently working on their own HPA projects for a number of years who could challenge Altech for new market share.

Orbite Technologies Inc. is a Canadian cleantech company which has developed a proprietary low-cost process to produce HPA from a variety of feedstocks, including aluminous clay, kaolin, nepheline, bauxite, red mud, fly ash and serpentine residues from chrysotile processing.

Orbite’s kaolin will be sourced from its Grande-Vallée aluminous clay deposit in Quebec, which contains an indicated mineral resource of 1.04bn tonnes with an average alumina concentration of 23.13%. The deposit also contains rare earths, which Orbite hopes to extract as by-products.

The company is looking to produce consistent quality 5N+ (see table) HPA at a rate of 3tpd from its plant in Cap Chat, Quebec, this year before ramping up to 5tpd.

Orbite’s HPA processing method has been under development since 2004 and consists of five stages: feedstock preparation; leaching; selective extraction of alumina; calcination; and acid recovery.

Feedstock is prepared by grinding the material into small particles, before hydrochloric acid is used to leach it at high temperatures, dissolving all the constituent metals except titanium.

Alumina and iron dissolve to form aluminum chloride (AlCl3) and other metals like ferric chloride (FeCl3). To extract the alumina, the resulting leachate undergoes precipitation to remove AlCl3 as aluminium chloride hexahydrate (ACH), which is then calcined to form HPA. 

The leachate can be further processed to remove hematite, magnesium, gallium, scandium and rare earths. In January 2016, Orbite announced that it had conducted preliminary research indicating that gold recovery from fly ash using its processing methods is potentially feasible. 

Among the advantages Orbite claims for its process are the ability to recycle red mud, a waste product of commercial alumina production, although the company will only be able to put this strategy into practise once its HPA facility is fully up and running.

HPA purity

HPA can be subdivided into various categories (see table). HPA in the 5N-6N bracket is commonly used in the liquid crystal display (LCD) and semiconductor industries in sputtering and thin film applications, while 4N purities are commonly found in LEDs, energy storage capacitors and Li-ion batteries, as well as in decorative and bright-finish applications. 

According to Norsk Hydro, a Norway-based producer of high purity aluminium, 4N8-5N purities are also in demand for Li-ion battery applications. Norsk Hydro produces HPA via the traditional bauxite refining process and currently sells its 4N8-5N products into the medical and cosmetic industries.

Orbite has stated that the premium HPA market requires 4N-5N purities, however Altech believes that the bulk of high-value demand is in the 4N category and is therefore concentrating on this grade.

In 2015, Orbite shipped samples of its 4N8 HPA to customers for testing and reported positive feedback, but subsequently upgraded some of its processing methods to achieve 5N5 purity – samples of which it also sent to customers.

In November last year, it successfully produced ACH, the precursor to HPA, at a purity of 5N8. 
Figure 3: Global HPA market volume share by 
product type 
Source: Persistence Market Research, Altech 

The race is on between Orbite and Altech to lock in customers for their respective HPA products. In September 2015, Altech signed a sales agreement with Japan’s Mitsubishi Corp. for exclusive distribution in the Japanese market, while Orbite has commenced a number of supplier qualification programmes.

If the HPA market grows to the extent these companies predict, then there should be more than enough demand to support both operations. Furthermore, successful proof of concept at a large commercial scale could create a significant new demand channel for kaolin and, in Orbite’s case, a way of dealing with the problem of growing stockpiles of toxic red mud. 

HPA Sonics

HPA Sonics is a third company attempting to break into the HPA industry with a new patented processing technology. Dr Frank Ferrer, HPA Sonics owner, contacted IM with details on his process.

"What my process has been able to do is to inhibit passivation," he said. Ferrer explains that aluminium in a metallic state has a high affinity to oxidisation, whereby it loses its "shining metallic reflection" by forming a layer of aluminium oxide on the meterial’s surface. This thin layer of Al2O3 inhibits the natural tendency to be oxidised, and is known as "Passivation". 

Ferrer told IM that "the disruption of passivation" is undertaken by "pitting of the protective film of Al2O3 […] thus accelerating and allowing a reaction that normally does not occur to move forward"

"The force used is that of ultrasonics which creates micro bubbles which form and then collapse (called Cavitation). This reaction is exothermic in nature thus requiring minimal amounts of energy to complete the reaction.

"Plus it generates an energy-carrying-hydrogen at a faster rate than that of electrolysis (one kilo of pure hydrogen in 30 min at a 2Kw energetic expense).

Ferrer goes on to explain why his technique can compete on price, "as you add three atoms of oxygen to the metallic aluminium you almost double the total weight of the HPA produced, thus cutting in half the cost of your aluminium stock needed to generate one kilo of HPA."

Ferrer also disputes the pricing his competitors use, claiming that "the Chinese market […] has lowered the market value of HPA Down to $10/Kg", whereas according to Altech, pricing is around the $23-25/Kg.

HPA Sonics hopes to commercialise their technique in 2017.

Orbite has produced HPA from its CapChat plant in Canada. (Source: Orbite Technologies Inc.)