Nominating Organization
United States Mint
Product, Process or Manufacturing Innovation Owner/s
Coin Product, Process or Manufacturing Innovation Release Date (Date made available to public)
Country/Countries of Implementation:
United States
Project Description
The United States Mint undertook a Circulating Blank Annealing Furnace Retrofit with a goal to reduce natural gas usage and pollutant output while maintaining thermal and operational characteristics of the furnaces utilized in the United States Mint’s plants in Philadelphia and Denver.
Project Team:
United States Mint
Positive Impact of the Project
The new zero carbon atmosphere created by the Circulating Blank Annealing Furnace Retrofit results in an overall reduction of the output of carbon dioxide and other greenhouse gas emissions by 2000 metric tons per year. As the United States Mint’s power providers continue to transition to renewable sources, the reduction of greenhouse gases will increase. Additionally, this has resulted in a reduction of energy required to ventilate the production area by also eliminating the production of carbon monoxide which is a byproduct of natural gas combustion to generate the exogas atmosphere. Lastly, the furnaces were retrofitted with higher efficiency recuperative burners to further reduce natural gas consumption.
Not only has this project led to the reduction of greenhouse gas emissions and fossil fuel consumption, it has also resulted in increased blank quality. The nitrogen/hydrogen atmosphere reduces the amount of oxides forming on the blanks during the annealing process which reduces chemical usage during post-processing and cleaning of coin blanks resulting in reduced wastewater output.
Safety at the facilities has also improved due to the elimination of flammable environment and the reduction of carbon monoxide generated. While hydrogen is now present, the 3% hydrogen ratio is not classified as a flammable atmosphere.
Innovation and Unique aspects
The Circulating Blank Annealing Furnace Retrofit reduces the environmental impact of coin manufacturing by the prevention of excess pollution output in the form of carbon dioxide, carbon monoxide and wastewater. This project also reduces resources required to manufacture coinage by reducing natural gas usage.
To achieve this, the protective atmosphere used in the annealing process was switched from the traditional exogas generated by natural gas combustion to a mixture of high purity gas at a ratio of 97% nitrogen to 3% hydrogen. Both of these gases are created in cabinet generators near the furnaces, utilizing electricity and water provided by the local utility company.
The proven success and benefits of the Circulating Blank Annealing Furnace Retrofit are in advanced stages of implementation in Denver, adding to the cumulative and growing benefits of the project for the United States Mint. This project serves as a model in environmental stewardship and sustainability; the United States Mint hopes that these documented achievements will become industry standard and will be adopted by other industries with similar heat-treating needs.
Environmental Impact
The tangible impact of this project is measured by the reduction of airborne pollutants (carbon monoxide, carbon dioxide) by 2000 metric tons per year. The reduction will continue to grow by as much as another 900 metric tons per year as the supply of renewable energy sources increases in Philadelphia. Another environmental benefit is provided through the reduced consumption of a natural resource, with the use of natural gas down 50% from 1.415 million cubic meters to 708,000 cubic meters. Additionally, this project has benefitted the coining operation through increased blank quality and improved operator and staff safety.
Main image that describe this project.
