Q & A on the situation in Hungary post bauxite residue area failure

What process is used to produce alumina?

Aluminium oxide or alumina, the raw material used for making primary aluminium, is normally made from bauxite using the Bayer Process; all alumina production plants in the EU employ the Bayer Process.

Bauxite is a readily available ore containing aluminium oxides and hydroxides in levels between 45 and 60 % by mass. Some bauxite is mined in Europe, although it is mainly mined in countries such as Australia, Brazil, West Africa and Jamaica.

In the Bayer Process, bauxite is dissolved in caustic soda at high temperatures and under pressure to form a solution of sodium aluminate along with a solid residue. The sodium aluminate is filtered and aluminium hydroxide crystals encouraged to precipitate; the aluminium hydroxide is then heated (“calcined”) to form alumina (aluminium oxide).
Over 90 % of the alumina produced in the world is used to manufacture aluminium metal, the remainder is used to make water treatment chemicals, as well as refractory products, ceramic materials, tiles, and glass.

What is “bauxite residue” and how is it being managed?

The bauxite residue, commonly called “red mud” is the solid fraction left over from the initial dissolution of bauxite in caustic soda. It is mainly composed of iron oxides, titanium oxide, silicon oxide and un-dissolved alumina, together with a wide range of other oxides, the presence and relative proportion of which varies according to the source of the original bauxite ore. The high concentration of iron compounds in the bauxite gives the residue its characteristic red colour.

A residual amount of the caustic soda used in the process remains with the bauxite residue causing the material to have a high pH/alkalinity.

The method of disposal of bauxite residue varies across the world, depending on factors such as land availability, technology availability, climatic & geographic conditions, logistics and regulatory requirements.

Companies are required to ensure that bauxite residue disposal areas comply with the respective environmental standards. Modern guidelines will include both general and locational specific design criteria such as soil conditions, earthquake risk, long term stability and management of storm events. Careful monitoring ensures structural integrity is maintained.

Alumina refineries try to maximise the recovery of the valuable caustic soda from the residues in order to reuse it in the production process; many plants in the EU achieve a recovery rate of at least 96 %. Apart from the residual caustic soda remaining after this recovery process, the ore residues do not contain any industrial additives. Over time the residual caustic soda associated with the bauxite residue are partially neutralised (the pH is reduced) by carbon dioxide from the air.

Once their storage capacities have been exhausted, red mud disposal sites are generally remediated.

How did this tragedy in Hungary happen?

The Hungarian Government authorities are investigating the causes of the dyke wall failure and the EAA has offered expertise to help determining both the appropriate measures to be undertaken in response to this tragedy and the causes. This dyke failure is the first accident of this type ever reported globally.

What are the potential health effects and measure that are to be taken?

Due to the residue’s alkaline nature, direct contact with eyes, skin or ingestion can cause corrosive effects the severity of which will depend on the nature of the residue, the alkalinity of the exposure, the duration of contact and the effectiveness of first aid measures such as rinsing with water or with other appropriate solutions.

For further details, please click here

What trace metals are present in bauxite?

Bauxite is a naturally-occurring and one of the most abundant materials in the earth crust. It is practically found everywhere on earth, though higher grade bauxite is traditionally found in the regions mentioned earlier. There are a wide range of metallic oxides present at low levels in the bauxite residues; they include the oxides of calcium, chromium, magnesium, manganese, vanadium, zinc and zirconium. In addition, trace quantities of barium, cadmium, mercury and nickel can sometimes be found depending on the source of the original bauxite.

Considering the low concentrations involved, acute adverse health effects from heavy metal exposure are unlikely to occur.

The exact composition of the red mud stored in MAL’s deposit will be known only after the results of the chemical analysis will be made available.

Is bauxite’s natural radioactivity an issue?

Bauxite is a naturally-occurring and one of the most abundant materials in the earth crust. It is practically found everywhere on earth, though higher grade bauxite is traditionally found in the regions mentioned earlier. Some of these bauxites contain very low levels of radioactive species, on a par with naturally occurring radioactivity found in granite rocks in various regions of Europe. The concentrations of naturally occurring radioactive materials such as uranium and thorium are very low in bauxite residues and are not expected to cause any adverse health effects.

How many red mud disposal deposits exist in Europe? How secure are they?

There are 7 alumina plants operating in the EU 27 in addition to the one in Hungary, most of which have deposits linked to the plant. In addition there are a number of bauxite residue storage areas associated with alumina plants that have closed down; most of these closed bauxite residue sites have now been remediated.

Today, EU legislation is in place to regulate the types of waste generated during all manufacturing processes, examples of such legislation include Directives on Mining Waste and Integrated Pollution Prevention and Control (IPPC). EAA members comply with all the necessary legislation and regard all matters relating to Health, Safety, and the Environment with the utmost importance. The maintenance of their facilities is a matter of the utmost importance in order to secure a safe, accident free, and sustainable future.

How has the European aluminium industry responded to the situation?

EAA, through its members’ networks have offered competence and expertise within a range of specialisations, to assist the Hungarian authorities with health, environmental and residue management issues. The EAA is coordinating industry contacts both with EU and Hungarian authorities.

Following the outcomes of the investigations, the industry will review and assess the results and adjust its practices if and where needed.

Click here for more information on industry’s best practices in the management of the bauxite residue (August 2014 update).

For further contacts:
Erich Cuaz
Public Affairs and Communication Director

European Aluminium Association AISBL
Avenue de Broqueville, 12
1150 Brussels - Belgium
Tel: +32 2 775 63 59
Fax: +32 2 779 05 31
cuaz(@)eaa.be
www.alueurope.eu

Chris Bayliss
Deputy Secretary General

IAI – International Aluminium Institute
Tel: + 44 7947 922295
[email protected]
www.world-aluminium.org