Emissions & Waste

 

In addition to greenhouse gas emissions, we are actively working to reduce other air emissions and our solid waste streams.

 
Emissions

We had mixed results in our efforts to reduce air emissions in 2013, with some showing significant declines and others increasing steeply after years of trending downward.

 

A 31% decline in our mercury emissions was due to lower mercury content in the bauxite we use in our refining process and improved control system management. Our sulfur dioxide emissions also declined by 11%, mainly because of lower sulfur content in the fuels we use.

 

Our nitrogen oxide emissions and fluoride emissions intensity both increased significantly, with jumps of 35% and 15%, respectively. The increased use of fuel oil and coal for alumina production contributed to the increase in nitrogen oxide emissions, as well as the increased use of diesel generators to facilitate boiler overhauls and maintenance at the Jamaican refinery. The 15% increase in fluoride emissions intensity was an indirect effect of capacity idling.

Air Emissions
  Mercury
Kilograms

Sulfur Dioxide
Thousands of metric
tons
Nitrogen Oxide
Thousands of metric
tons
Fluoride
Kilograms per metric ton of aluminum produced
2009 2,922.5 35.5   6.6   0.62  
2010 3,727.6 49.0   8.7   0.98  
2011 4,606.1 30.5   8.3   1.44  
2012 3,261.9 35.8   8.1   0.75  
2013 2,252.0 32.0   10.9   0.86  

 

Landfilled Waste

The amount of waste we landfilled in 2013 declined 21% over prior year. This achievement was due to continued work in finding new uses for the following process byproducts:

  • ESP dust, which is the alumina collected by a refinery’s dust-collection system;
  • Sweeping alumina, which is the alumina powder that is swept up from a smelter’s potroom floor;
  • Spent pot lining, which is the carbon cathode and refractory material removed from the smelting pot at the end of its useful life; and
  • A variety of carbon products.

 

To a lesser extent, capacity idling also contributed to the reduction in landfilled waste.

 

We sold or recycled 59,546 metric tons of waste in 2013, a 15% decline after four years of growth. Idled capacity and fluctuations in demand were behind the drop.

Solid Waste
Thousands of metric tons
  Landfilled Waste Wastes Sold or Recycled
2009 32.8 49.9
2010 25.7 58.9
2011 18.5 65.0
2012 14.0 70.4
2013 11.0 59.6

 

Spent Pot Lining

Spent pot lining (SPL)—a waste from our smelting process—is generated when the carbon and refractory lining of smelting pots reaches the end of its serviceable life. 

 

In 2013, we generated 7% less SPL compared to 2012 due to the idling of smelting capacity.

 

Globally, we have led the aluminum industry in finding ways to transform SPL into a raw material for other industries, such as cement manufacturing. Our recycling/reuse efforts in Latin America and the Caribbean not only accounted for 100% of the spent pot lining we generated during 2013, but also a portion of the material that had been in long-term storage.

Spent Pot Lining
  Generated
Kilograms per metric ton of aluminum produced
Recycled/Reused
Percent

2009 9.1    160   
2010 18.2    195   
2011 19.5    61   
2012 17.3    96   
2013 16.1    142   

 

Bauxite Residue

Bauxite residue, which is generated during the alumina refining process, is made up of two components of roughly equal quantity—sand and mud—along with some residual caustic soda. The residue is stored in impoundments that are capped and re-vegetated when full.

 

Globally, we have  three strategic sustainability targets related to the land required to store the material, rehabilitation of the storage areas, and recycling and reuse of the residue. The latter goal is proving to be the most challenging globally, although we are making progress in developing and testing possible solutions.

 

Both the Federal University of Sao Carlos (UFSCar) and the Polytechnic School of University of São Paulo (Poli) in Brazil are helping us develop new applications for bauxite residue in the cement industry. One application is using bauxite residue as a raw material in the production of clinker, a limestone and clay material used to make cement. The second is substituting bauxite residue for clinker.

 

We are also working with the Federal Alfenas University on neutralizing the caustic aspect of bauxite residue through long-term interaction with live microorganisms and extreme weather conditions. If successful, the project would result in lower-cost storage methods that are more environmentally friendly.

Bauxite Residue
  Generated
Metric tons per metric ton of alumina produced
Reused
Percent

2009 0.96   0    
2010 0.90   0    
2011 0.85   0    
2012 0.85   0    
2013 0.80   0