A longtime producer of wheat flour for glue extenders used in the wood products industry, Idaho Milling and Grain recently implemented a process that significantly reduces the production time while improving quality.

Glue extenders are used to bond thin sheets of layered wood veneer that form structural plywood. These compounds are also key elements in adhesives, sealants, coatings, plastics and cleaning compounds.

Idaho Milling reduced its glue extender production time from 2 hours to 20 minutes per batch cycle by replacing its existing ribbon blender with a Munson Model 700-TS-110-MS rotary batch mixer. In addition to increased product quality, the company said it was able to practically eliminate residual material in the machine after each batch.

Uniform Blends

The flour production process begins with the raw wheat stock. The wheat is tested for moisture and protein, blended to a target protein content and cleaned to remove foreign residue. Afterward, it is tempered by adding water to toughen the bran coat. The wheat is then milled into glue extender by running it through a series of roller mills, sifters and purifiers.

It travels by pneumatic line into the 110-cubic-foot (3.1 cubic meter) capacity Munson rotary batch mixer where it is blended with proprietary ingredients. The finished extender is then conveyed pneumatically to storage bins for packaging.

“The rotary batch mixer produces much more uniform blends, even with diverse particle sizes and variations in bulk density,” says Boyd Hess, head miller. “This is due to the mixer’s tumble, turn, cut and fold action, achieved with proprietary internal mixing flights and continuous rotation throughout the blending cycle.”

The system is controlled by a programmable logic controller. A recipe is entered into the PLC. A pneumatic system feeds each ingredient from several bins through airlocks until the mixer load reaches its target weight. When the airlocks shut off, the mixing action begins, lasting from 3 to 10 minutes depending on the product density. When done, the mixer discharge gate opens, and the discharge airlock valve meters the material to the packaging area until the load cells again indicate zero weight. The glue extender is packaged in 50- and 100-pound bags and bulk bags up to 3,000 pounds. “We can fill, blend and empty the mixer in less than 20 minutes for most formulations versus a typical batch cycle time of 2 hours using the ribbon blender,” says Hess.

“Another plus,” he adds, “is that there is nearly complete discharge without residue. In filling a 3,000-pound bulk bag, only 3 or 4 pounds of residual material remains in the mixer, if that.”

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