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Borates for Metal Recovery and Recycling: Adding Sustainability to the Metals Mix

:: Thursday, August 13, 2020 :: Posted By Maryam Moravej

For thousands of years, humans have refined and worked metals into objects of utility and beauty. Through the application of heat—and select additional components—metals lend their strength and flexibility to an infinite variety of uses.
 
One of the most wonderful things about metals is that once they have served a lifetime of use in one form, they can be transformed again, making them a practical go-to material for everything from heavy industry and construction to electronics, batteries, household products, and even art.
 
Borates are key to metal recovery and recycling processes that help to ensure more efficient and environmentally sustainable metal use across industries. As a major global supplier of borates for metal producers and recyclers, U.S. Borax offers both a variety of borate products and the expertise and technical knowledge to ensure metal recyclers and producers have access to the right borates for their applications and processes.


Metal recovery and recycling: Essential in manufacturing supply chains

Recycling and recovery are two sides of the same coin. Recycling is reprocessing scrap or waste metal into new products. Recovery is the process that extracts the purified metal from the scrap. Recycling and recovery of metals such as brass, bronze, copper, lead, zinc, and aluminum can come from scrap or from slag that is left over from a primary smelting operation. Metal can be recycled repeatedly without degrading its desirable properties.
 
Recycling and recovery of metals provide significant benefits for industry and for the environment:
  • Recovered and recycled metals are available at a fraction of the cost of virgin metals
  • Scrap provides a continuous source of material
  • Energy consumption for recovery and recycling is dramatically less than purifying metal ore: Recycling aluminum and copper, for example, uses 90-94% less energy than producing new metal
  • Manufacturers can source recycled metals closer to home, through local or regional scrap sources
Scrap metal is not waste, it’s a resource. And for many manufacturers, it’s an essential key to their supply chain optimization.
 

The power of borates in metal recovery and recycling

Producing a pure metal product requires removing all oxides and extraneous impurities. Borates help by acting as fluxes during melting, combining with metallic oxides at relatively low temperatures to bring them to the surface of the melt as a slag that can be decanted or skimmed off.
 
The flux effect is different for different metals—and in different processes. For example, in aluminum production, boron in the form of fluoboric acid (HBF4) is used as flux for aluminum reduction. During aluminum production, boric oxide added to the pot lining has shown to be a suitable reactant to decrease the formation of cyanide, a hazardous waste. Boron is also a grain refiner and hardening agent for aluminum.
 
Borates are not the only flux agent that can facilitate metal recovery processes. Other fluxes include lead carbonate, soda ash, silica, scrap iron, or combinations of multiple fluxes. However, borates offer marked advantages over other flux agents. Borates:
  • Produce a high-solvent action on metal oxides and siliceous materials, resulting in a purer metal product
  • Reduce liquidus temperature, enabling formation of highly fluid slags and the extraction of more metal from the slag
  • Enable easier thickening and skimming of slags depending on metal chemistry
  • Reduce manufacturer’s energy costs because a lower melting point is required in the furnace
  • Reduce the leaching effect of lead sulfate from slag in lead recovery, which enables improvements in the cooled, more solidified slag
  • Are easy and safe to handle
  • Are non-combustible and have minimal fuming tendency

Your choice of borates for metal recovery and recycling matters

Given the nature of a fluxing agent in metal recovery, it might seem that any borate could do the job. Any superfluous materials would simply be carried away in the slag, right? However, the type of borate product you choose for your process can influence the safety of people, equipment, and the environment.
 
For example, 20 Mule Team® Borax Neobor® (a hydrated borate) is the most common form of sodium borate used in industry. It might seem like a simple choice for a smelting operation, too. And in many operations, it is an excellent choice. However, the effects of Neobor and Dehybor® in a smelting process are quite different.
 
As Neobor’s sodium borate heats up, it dehydrates slowly and forms a melt that tends to bubble and sputter as it loses additional moisture. In smelting operations, anhydrous borates such as Dehybor help to avoid sputtering—and even potential steam explosions—making them a safer choice.
 
In metal recovery smelting, Dehybor improves both process quality and safety. It is an excellent solvent for metallic oxides at high temperatures. In addition:
  • Hydrated borates may be more corrosive to refractory brick because of the water they emit.
  • Because Dehybor is already dehydrated, less product is required per ton of recycled material, which may deliver cost savings to manufacturers.
  • As a refined borate, Dehybor (like other U.S. Borax products) contains the lowest possible amount of toxic elements such as arsenic. As a result, Dehybor releases fewer toxins into the environment during smelting.
  • In gold recovery, the formation, purity, and consistent granulometry of borates are important. Dehybor’s consistency makes it the ideal product for preventing “spit and crackle” problems and facilitating the proper melt.

The know-how you need to select the right borate

For scrap metal recyclers, U.S. Borax is a reliable and experienced partner. Whether your facility is a small manufacturing operation or a large distributor, we enable on-time delivery through our established logistics operations and global warehouse network.
 
But we go beyond the sale, offering technical support to help ensure the right product and right use for your application. Turn to us for guidance on the function of borates in your process, samples for testing, and recommendations for formulations based on our extensive research and experience.
 
Together, we can ensure the efficient use of metals—and solve one of the significant challenges of modern living.

 

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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