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Chinese outages a reminder of aluminum dirty secret – Mr Andy Home

Metal News - Published on Wed, 22 May 2019

Image Source: Reuters UK
Reuters reported that Chinese alumina prices have jumped to a five month high on news that at least two refineries in the province of Shanxi are being shut down pending environmental inspections. So far the market impact seems localized. Shanghai aluminum prices have risen on concerns about the potential knock-on effect on metal production in China. Alumina is the intermediate product derived from bauxite used to smelt aluminum. But the price of alumina traded on the CME is unmoved, reflecting expectations that the giant Alunorte alumina refinery in Brazil is poised to receive official sign off to return to full production after more than a year of operating at half capacity.

The metal touted for its environmental benefits, particularly in the manufacture of lighter cars and trucks, has a big problem with storing its toxic by-products.

With the world’s focus on tailings dams after the Brumadinho iron ore disaster in Brazil, aluminum has just received another reminder that it, too, has a tailings problem.

Most of the world’s refineries use the Bayer process to extract alumina from bauxite.

The waste product is red mud, a mix of un-dissolved alumina, iron oxide, silicon oxide, titanium oxide and multiple other metals in smaller quantities. It’s the iron oxide that gives the residue its distinctive red color.

The most common way of dealing with red mud is storing it in tailings dams or ponds.

And there’s a lot of it around; more than 3 billion tonnes, according to the International Aluminium Institute, which describes red mud as “one of the largest industrial by-products in modern society.”

A tonne of alumina on average generates about one-and-a-half tonnes of red mud, though the ratio varies depending on the type of bauxite processed.

Last year there were 160 million tonnes of residue produced. And as global alumina and aluminum capacity rises, the amount of residue will also rise to a forecast 250 million tonnes in 2030.

Red mud briefly grabbed the headlines in 2010, when a dam spill at the Ajka refinery in Hungary flooded the surrounding area, killing 10 people and leaving many more with caustic burns from the highly alkaline waste material. The plant was closed permanently.

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Posted By : Rabi Wangkhem on Wed, 22 May 2019
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