Processing Magazine

Prince Minerals Adds “Brick Belt” Capacity for High-Quality Colorant

June 24, 2008
Prince Minerals, Inc. is a leading producer of specialty mineral products with emphasis on naturally occurring minerals and pigment applications. Its products are used in bricks, refractories, glass, ceramics, foundries, cement, and other applications. The company operates six processing plants, including the newest, a 40,000 sq. ft. facility in Monroe, NC. that’s also home to an extensive R&D lab and Technical Service Center. The North Carolina location, which began production in March, 2008, was chosen for its close proximity to the company’s growing “Brick Belt” customer base, which spans the Carolinas and Georgia.

Two main production “circuits” comprise the Monroe facility. A dedicated line for the manufacture of proprietary “through-the-body” pigment blends for the clay brick and colored mortar industries produces in bulk at a rate of 10 to 15 tons per shift. Colorant is stored in silos.

A second, commercial line, produces specialized dry-mix surface colorants for the structural clay brick and tile industries. For the design and manufacture of this larger line, Prince Minerals worked with Ingredient Masters, Cincinnati, Ohio. The firm specializes in precision batching systems and has extensive credentials in the brick (Redland Brick), ceramic (Oceanside Glasstile) refractories (Uni-Ref, Spar Refractories, Zedmark) and colorant (Englehard) industries.

Jon Attridge was Construction Facility Manager, and led the team that developed the requirements for the line. He brought to the project an unusual cache of qualifications. Explains Attridge, “I’m an R&D guy, a ceramic engineer whose focus is colorant development.” For the ten years Attridge has been with Prince Minerals, his area of specialty has been colorants for the brick industry.

Attridge’s family’s business, however, is mechanical contracting, and he has a background in that discipline as well. “Developing the line was the perfect challenge for me,” he says, “knowing I’d be senior at this plant, with a vested interest in its success both operationally, and financially.”

The goal for the commercial circuit, according to Attridge, was to build “a flexible batching line that would produce consistently high quality product, with virtually zero rework. We also wanted to optimize the ergonomics of the operation by eliminating manual tasks, such as bag cutting, and have the cleanest possible work environment, by preventing material from becoming airborne when dispensed. Finally, we looked for a system concept that was industrial, rather than food grade or something else,” adds Attridge, “and a supplier with an understanding of the industrial environment.”

After substantial research, and consideration of the approaches of several manufacturers of batching systems, Prince Minerals chose the system concept recommended by Ingredient Masters.

The heart of this system is a sequence of 54 cu. ft. polyethylene dispensers, each with a bulk bag lifting frame. The dispensers are arranged in facing rows of a dozen each and have a common support structure and dust pickup system.
Each dispenser holds a single ingredient and is modular in that it can be easily removed from the line. Bulk bags – “Super Sacks” - of raw material are suspended above the bins at a 12’ elevation.

Beneath the bins, an operator-driven, motorized scale cart moves on a track. Ingredients, target weight and tote locations applicable to the selected recipe are entered into a program. The cart then moves down the track and the correct proportions of each ingredient are released through a valve into the cart’s hopper. Materials can also be added from Super Sacks, or in bulk from an outside silo. Batch accuracy is +.2 lbs.

When the batch is complete, the hopper is retrieved by a fork lift and emptied into a mixer. After blending, and testing, finished product is conveyed pneumatically to one of the storage silos, then to the bagging facility. 50% of the finished product is packaged into 50-lb. bags; the rest in bulk bags of 1000 to 2000 lbs. “We get precise weights into the Super Sacks just by hitting a button and spec’ing the weight,” says Attridge, “but that’s not the end of the story. There’s still a 24-hour quality control process before batches can be shipped.”

Explains Attridge, “a master standard has been established for each color blend. Finished products are tested for fired color that follows customer firing parameters. Incoming raw materials are subject to quality protocols we developed. In either case, a sample is taken from each batch and tagged for firing and rheological tests. Samples are suspended in water, applied to test substrates or tiles, and fired at 1900 to 2000oF. The next morning, they’re read with a spectrophotometer, which gauges color against the standard.

“If approved,” he continues, “that batch is Ok’d for shipment. If alterations are required, material is returned to the mixer, adjusted for color and rheology, re-sampled and tested again.”

The system engineered for Prince Minerals is a lean, manual system that offers exceptional flexibility, and the ability to automate or expand as needs evolve. Says Ingredient Masters President and Owner Scott Culshaw, “Prince Minerals has a commitment to supply a pre-qualified, pre-checked product. They needed to know when it’s shipped to a customer and fired as designed, it will be accurate to the standard.”

Another advantage of this equipment, according to Culshaw, is that Prince Minerals’ customers “have no need to maintain inventory, but rather just a dozen or so preblended formulas.”

In addition to the primary production line, Ingredient Masters also supplied equipment for a third line, similar in design, that incorporates 3 feed hoppers, mounted above a 200 cu. ft. mixer.