When Jeff Wyers became the plant manager of Nash Brick Co. in Rocky Mount, N.C., 5 1⁄2 years ago, he experienced this type of difficult raw material problem firsthand. The locally mined clay and shale mixture used to make Nash Brick’s red face brick had very little plasticity, and as a result, the plant’s product losses were high. For years, the plant had been using liquid sodium silicate to aid in extruding and setting its brick, but its losses were still averaging greater than 10%. For a plant making more than 30 million modular brick equivalent (MBE) per year, such high losses were having a definite impact on profits. “Without the sodium silicate, our losses were higher than 50%, so the sodium silicate definitely helped,” says Wyers. “But we never really understood the sodium silicate, and the people who were selling it to us didn’t understand it either, so we couldn’t reduce our losses beyond 10%. We tried several other additives, but we couldn’t find anything that worked better than what we were already using.”
Wyers was frustrated, but he didn’t know where else to turn. Then, in the summer of 2000, he received a call from Terry Cowhey, vice president of sales and marketing for International Protein Colloids, based in St. Joseph, Mo. According to Cowhey, what Nash Brick needed was protein.
“Natural collagen-based protein polymers have been used for centuries as binders in woodworking, bookbinding, textiles, tape and paint. But they also hold a great deal of potential for other products that require binding and lubricating properties—including brick,” Cowhey explains. “The polymers act as a dispersant, spreading around the particles and forming a tough adhesive film. As a result, stress cracks or breaks experienced during product handling can be significantly reduced or even eliminated. Additionally, the increased lubricity provided by the polymers can reduce the extruder’s power consumption or provide increased extrusion rates, and there are also a number of other potential benefits.”
For the next nine months, Wyers ran a number of tests with the polymers, working closely with Cowhey to test both the benefits and limitations of the product in brick applications. “We tested a number of different formulations at different add rates, using a stopwatch and five-gallon pails with holes in the bottom to add the product to our raw material mix,” explains Wyers. “We tried changing our tack times, and increasing and decreasing our lubricity. We collected data on recovery and fired properties, and we tried adding the polymers at different places in the process to see what effect it would have on the brick. Once we got a polymer product that we thought was where it needed to be, then we started adding it to our raw material mix at the pug mill using a 260-gallon tote. We added a pump with a flowmeter to the line running from the tote to the pug mill so that we could precisely determine our add rate.”
Nash Brick has been using the protein polymers on a consistent basis since the summer of 2001. According to Wyers, the benefits of using the proteins have been remarkable—especially for the company’s special shapes. “Before we started using the proteins, special shapes were extremely difficult for us to make without cracking or breaking. Now we load them up with proteins and run them through without any problems. Our loss rate on all of our products has dropped to around 3%, and we haven’t experienced any residue, burnout problems or other negative effects,” he says.
Additionally, although the proteins are more expensive compared to the sodium silicate, a lower add rate is enabling the company to save money on additives. “We were using a rate of 6 gallons per kiln car (3360 MBE) with the sodium silicate,” explains Wyers. “With the protein polymer, we only need to use about 1.9 gallons per car to get the maximum benefit. So even though the protein is much more expensive, the lower add rate and higher recovery make it economically beneficial.”
Wyers cautions that the add rate would likely vary from plant to plant, depending on the raw material characteristics and the plant’s desired goals. Since Nash Brick’s main objective was increased recovery, the company experimented with different amounts until it achieved the best possible results. “With 1.4 gallons per car, we could tell that the protein was there but it wasn’t really providing any measurable benefits. At 1.6 gallons, it began to make a significant difference. At 1.8 gallons, it made a tremendous difference, and 1.9 was the point of no return. We tried putting in 2.5 gallons per car, but it really didn’t do anything more than 1.9 gallons. It’s a very steep curve—when the proteins start working, they start working quickly on an add rate basis,” says Wyers.
The increased lubricity provided by the proteins can also reduce the power requirements for the extruder, leading to energy savings and, perhaps even more importantly, savings on equipment repair. “Compared to the sodium silicate, we were able to reduce our amperage by about 5%,” says Wyers. “And if you’re going faster at a lower amperage, your wear part usage is probably going to go down as well.”
According to Wyers, some brick plants might be able to achieve an even greater level of energy savings with the proteins. For Nash Brick, however, increased product quality was the main goal; the reduction in amperage was merely an unexpected side benefit. “We actually put in a little less water than what we had to with the sodium silicate and let the amperage come back up slightly so that we can run a much stiffer column,” Wyers explains. “We used to run a column that was around 3.5 in. on a penetrometer; now we can run one that’s in excess of 4. That means much less water we have to take out in the dryer, and it also helps our recovery rates.”
However, companies that would prefer to work with a dry material and either mix it with water themselves or add it to their product in a dry form also have the option of doing so. For plants like U.S. Brick (a division of Hanson Brick America) in Minerals Wells, Texas, which has been using the protein polymers in production since the summer of 2002, the ability to use a dry additive has provided a significant cost advantage. “We get the proteins in bags as a dry material and mix them as needed—we don’t have to store them in a 10,000-gallon tank like we did with the previous liquid additives we were using,” explains Curtis Adams, plant manager. “We store the dry proteins on pallets in our material storage rooms and mix them up as needed a day ahead of time, so they’re much easier to use. They’ve also saved us about $8700 per year compared to one additive we were using, and over $100,000 per year compared to another material, due to the reduced shipping costs and lower add rates required.”
According to Cowhey, these benefits are just the tip of the iceberg. “We’re really excited about the potential for the protein polymers in brick applications,” he says. “The proteins provide the ability to create much lighter weight, stronger bricks—in fact, Nash Brick has been able to increase the number of finished cubes shipped on each truck from 20 to 24 cubes because of the weight reduction. Some plants are also using the polymers to adhere fiberglass insulation to their kiln cars. Unlike conventional wheat paste adhesives, the proteins won’t attract animals into the plant, and they won’t dry out. They can be applied to the insulation hours before the insulation has to be attached to the kiln car, providing a great deal of time and labor savings for the kiln operator.”
Cowhey adds that one specific protein polymer mixture could also potentially be used to replace barium carbonate in some brick formulations, thereby reducing or even eliminating scumming. And because the polymers are made from naturally occurring proteins, they are completely biodegradable and don’t pose any health or environmental concerns.
“We’ve really just begun to evaluate all of the potential benefits,” says Cowhey. “I really think there are many more things the proteins can do for the brick industry.”
For more information about Nash Brick, contact the company at P.O. Box 962, Rocky Mount, NC 27802; (252) 451-7813 (production) or (252) 443-4965 (sales); or fax (252) 443-4061.
For more information about U.S. Brick-Hanson, contact the company at 8851 Hwy. 80 West, Fort Worth, TX 76116; (817) 244-9191; fax (817) 244-8866; or visit http://www.usbrick.com.