Hindalco turns environment-harming product into a money-minting resource

The aluminium maker's breakthrough in regenerating red mud for the construction industry addresses a serious environmental concern

The safe storage of red mud, a highly toxic by-product in the process of producing alumina, has been a perennial problem of aluminium manufacturers. Recently, however, Hindalco Industries surprised the global aluminium industry by finding use for the complete regeneration of red mud at its three alumina refineries. Working closely with cement groups, Hindalco Managing Director Satish Pai said the company had developed a “high grade material for the construction industry” from red mud.

The idea is not novel. As an industry official pointed out, some aluminium producing countries have started processing red mud for cement making on a pilot scale. But Hindalco has expanded the operation considerably; it targets supplying 2.5 mt of processed red mud to cement manufacturers.

This will fulfil three objectives. One, to the extent red mud is used in cement making, it will be a substitute for mined minerals such as laterite and lithomarge, leading to resources conservation. Two, the transition of red mud from an environment threatening by-product of alumina to a cement-making ingredient makes aluminium-to-copper producer Hindalco a more comprehensive practitioner of the circular economy. Three, and perhaps most importantly, Hindalco’s success will encourage the country’s other two integrated aluminium makers, Vedanta Aluminium and National Aluminium, to step up their R&D efforts to convert an environment-harming product into something of value.

Expectedly, UltraTech Cement, the country’s largest producer of the binding material with a capacity of 117 mt, will receive the biggest share of Hindalco’s red mud supply. Under a new agreement, Hindalco will be supplying annually 1.2 mt of red mud to 14 UltraTech units in seven states.

The accumulation of red mud beyond a certain level in tailings dams, especially during the monsoon, poses the threat of dam bursts or overflow of toxic water submerging surrounding areas and finding its way into rivers or rivulets. The annual disposal of red tailings of a volume equalling their generation at three refining units is insurance for Hindalco against accidents killing or injuring people and polluting river water, as seen at Ajka in Hungary in 2010 and more recently in China and Brazil.

Last year, in fact, Hindalco was the victim of an incident linked to its alumina refinery at Muri in Jharkhand, leading to a temporary suspension of operations. Commissioned in 1948 by the former owner, Indian Aluminium, the 450,000 tonne Muri refinery on the banks of Subarnarekha river is the country’s oldest.

But tailings dam collapse is not unique to the aluminium industry. The collapse of a dam holding iron ore sludge of a mine owned by Brazilian Vale on January 25, 2019, which killed nearly 300 people, will continue to haunt miners all over the world. As with red mud, the challenge here, too, is to derive value from iron ore slime that accumulates in tailing ponds in the process of mining.

Bhilai steel plant has risen to the challenge of recovering around 1.2 mt of ore from its Dalli tailing pond in Chhattisgarh, holding an estimated 19 mt ore with low iron (fe) content of 54 per cent. SAIL Director Anirban Dasgupta says: “We should be able to raise the fe content to 64-65 per cent through high quality beneficiation. The mission is to convert an environment compromising waste into wealth.”

What the Bhilai plant has done should set an example for all captive and merchant iron ore miners in the country. Bhubaneswar-based green activist Deenabandhu Satapathy says: “Whether it is bauxite mining leading to alumina production locally or iron ore and chrome ore extraction, Odisha has the largest profile among all states. The country’s three white metal producers have large alumina refineries in the state and their capacity is growing. So the industry and the state have to be watchful that at no point there is seepage or overflow of red mud.”

Growing volumes of red mud are a major concern for countries hosting alumina refineries. No wonder provincial governments in China are required to intervene to discipline alumina producers. This includes mandating plant shutdowns when red mud spillage kills people and damages cultivable land and river water. China has grown the industry at a fast clip in the past two decades to the extent that last year, it had a share of 35.797 mt of world aluminium production of 64 mt. In alumina, it accounted for 72 mt in global output of 132.351 mt.

But while building smelters and refineries, the Chinese groups ignored environment and safety concerns. Now, in the face of rising global criticism and also to cut pollution, China is phasing out environment unfriendly smelting and alumina refining capacity. For example, last year, Xinfa group had to close a 500,000-tonne smelter at Xinjiang following an explosion.

Producing a tonne of alumina generates around one-and-a-half tonnes of red mud. The exact generation of red sludge will depend on what quality of bauxite is fed into a refinery as well as the technology in use. Globally, the industry generates over 160 mt of red mud held in ponds over large tracts of land.

According to the International Aluminium Institute, the world has over the years accumulated more than 3 billion tonnes (bt) of red mud, most of it in China. The material is among the largest industrial by-products of modern society. With projected future rises in alumina production, the world will have to contend with annual red mud generation of 250 mt by 2030. This underlines the urgency of broadening industrial application of red mud beyond cement and bricks to ferrous metal on which Rusal, the world’s second-largest primary aluminium producer, is now working.