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Borates and Sustainability in Glass Manufacturing

:: Wednesday, August 18, 2021 :: Posted By Allen Zheng

Glassmaking has existed for thousands of years, and it’s still one of the most exciting and promising modern technologies on earth. Advances in industrial production methods—including the addition of borates to glass formulations—have improved factors such as production output, precision composition, and resistance to thermal shock, enabling an incredibly diverse and growing set of applications.

But glassmaking is also inherently resource-intensive. Because glass is used in numerous applications, from retail packaging to laboratory glass to printed circuit boards, glassmaking is a significant producer of greenhouse gases.

Today, glass industry leaders around the world are committing to aggressive carbon dioxide (CO2) reductions and adopting a multi-faceted approach to reach those goals. And, U.S. Borax is here to support them.

Boric oxide in glass manufacturing

Modern glassmakers use borates in their formulations to produce products essential to modern life, including insulation fiberglass for energy savings in buildings, textile fiberglass for electronics, and display glass for LCD screens.

Adding boric oxide to glass benefits both the glass properties and the manufacturing process. The presence of boron in glass also enhances the durability and chemical resistance of the end products.

Adding boron in the manufacturing processes significantly lowers the melting temperature required for glass production. A lower temperature in the furnace means less fuel is required to melt the materials, leading to improved energy efficiency—and reduced carbon emissions.

Boron is a volatile element, so using borates may add a certain level of technical complexity. Thus, choosing the right boron product is important to help maximize the environmental benefits and balance them with costs and other considerations.

Challenges and opportunities for improving sustainability in glass manufacturing

Regulatory bodies around the world are putting increased pressure on all heavy industries to decrease their carbon emissions. That top-down regulatory pressure, along with a variety of economic factors, is driving glassmakers to explore ways to improve the sustainability of their processes.

On the regulatory side, many glass makers are already required to comply with existing limits on air emissions for NOx, SOx, and dust particulates, and the industry is expecting further restriction on carbon discharge and certain volatile species.

From an economic perspective, the industry is realizing that in the long run, initiatives that improve sustainability will also improve profitability by decreasing energy costs and improving productivity.

Four emerging approaches to CO2 reductions in the glass industry

Leading companies in the industry are actively exploring approaches to meet international sustainability goals. The effort leverages four broad strategic areas:

Improving production efficiency in furnaces through process and raw materials optimization

In the glassmaking process, efficiency gains come from:

  • Optimizing burners and furnace geometry
  • Converting air-fired furnaces to oxy-fuel combustion
  • Improving productivity and product quality to reduce unit energy consumption

These changes are all enabled by advanced development of energy demand measurement and modeling, which is also a sub-focus for glass sustainability. Efficiency improvements also come from optimizing raw material use. For example:

  • Enhancing recycling capability and promoting higher usage cullet
  • Choosing calcined limestone and dolomite for CO2 reduction
  • Choosing the right size of batching materials to enable new glass melting techniques to perform optimally

Improving heat recovery systems further conserves fuel

A large part of the energy loss in glassmaking occurs when waste gasses are released thought the furnace flue. Heat recovery systems like OPTIMELT® thermo chemical regenerator (TCR) technology developed by Linde capture this hot gas and repurpose it.

Other practices also reduce heat loss:

  • Better thermal insulation of the furnace
  • Installing equipment that utilize waste heat to preheat raw materials (ie, cullet)

Using sustainable energy sources reduces emissions

Glass industry leaders are exploring the use of alternative and low-carbon fuels such as hydrogen, biomass, biogas, ethanol, and even solar energy. Likewise, the use of electric furnaces is being tested. These innovations are promising, though they also bring different challenges to the glassmaking process.

CO2 capture is the most challenging approach in play

Multiple carbon-capture technologies are in development across a range of industries. Currently, most can be prohibitively expensive in the context of glassmaking. In addition, carbon capture itself requires energy consumption. However, for capture of emission species such as SOx and NOx, mature technologies are in place for leveraging catalysts and absorbents to effectively reduce emissions.

U.S. Borax: An invested partner in glass making and emissions reduction research

U.S. Borax, as a part of Rio Tinto, is committed to supporting the industry’s efforts to achieve better sustainability in glassmaking. We are committed to research and innovation supporting the positive role boron plays in lowering carbon emissions and reducing the emissions of our own boron mining operations. Our investments in research and development with glass industry partners will continue expanding our understanding of how each of our products behave with the latest fuel sources and furnace types.

  • We are partnering with Linde to validate that borosilicate glasses are compatible with their OPTIMELT TCR system, which shows promise as a way to increase fuel efficiency and improve productivity in glass furnaces without incurring major capital expenses.
  • U.S. Borax is looking for a solution that will make anhydrous sodium borate compatible with a broader range of furnace types.
  • We help customers choose the right borate for their application by quantifying the impact of their carbon footprint with a different choice of borate materials.

U.S. Borax is committed to sustainability

By partnering with innovators in the industry, we are working to make sure that any capital investments our glassmaking customers make will pay off in overall increased efficiency and lowered emissions.

As always, our research scientists and technical support team are available and ready to help industry leaders evaluate which levers for reducing emissions are most viable for their situation.

Resources

U.S. Borax, part of Rio Tinto, is a global leader in the supply and science of borates—naturally-occurring minerals containing boron and other elements. We are 1,000 people serving 500 customers with more than 1,700 delivery locations globally. We supply 30% of the world’s need for refined borates from our world-class mine in Boron, California, about 100 miles northeast of Los Angeles.  Learn more about Rio Tinto.

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