Montana mill raises the ante on state-of-the-art standard
January 01, 1999
by Teresa Acklin
By L. Joshua Sosland
Since the early 1980s, increased automation has been the Holy Grail of milling companies looking to build the most technologically advanced flour mill. But with the completion of its construction/renovation project at Great Falls, Montana, General Mills, Inc. may have moved the expression “state-of-the-art” in an entirely new direction.
In installing new on-line systems for measuring a range of flour characteristics, the company may have initiated a paradigm shift for quality control in U.S. flour milling which is not to say that increased automation was not an important part of the General Mills projects completed recently.
Total capacity at the Montana mill was raised 80%, but only one additional employee was hired to operate the facility.
The projects were completed in 13 months at a cost of U.S.$12 million. General Mills raised the daily milling capacity of its Great Falls B unit to 290 tonnes of wheat flour. In addition, a C unit was built, with daily milling capacity of 140 tonnes of semolina. The C mill also has the potential for a 140-tonne expansion.
The new durum mill construction followed the signing of a long-term semolina supply agreement with Pasta Montana L.L.C., a new pasta company that constructed a pasta plant adjacent to the General Mills mill. The company receives semolina via a pneumatic pipe connecting the two complexes.
The General Mills facility at Great Falls has a rich history, dating back to 1893, when it was a 27-tonne mill called Royal Milling Co. The mill always has been owned by General Mills or its predecessor, Washburn Crosby Co., although it was initially incorporated separately. It was General Mills' first flour mill outside the Minneapolis area, preceding the construction of a 320-tonne flour mill at Buffalo, N.Y., by 10 years.
Over the years, the mill was expanded several times. Eventually, the A mill, a wooden structure, was torn down. The B mill was built in 1917, modernized over the years and continues to operate today.
From the 1920s, changes at the mill were gradual. In the late 1950s, a Bemis packaging line was installed. Pneumatic systems were added in the 1980s and capacity was raised to 230 tonnes from 140 tonnes. Five years ago, automatic palletizers and polybundlers were installed. The mill has run consistently more than 300 days per year.
It was because the B mill was running so heavily that plans for an expansion already had been drawn up when Pasta Montana first contacted General Mills in February 1995. A decision largely had been made to raise capacity 20% through the addition of two new double-high roller mills and sifters and by replacing the existing purifiers.
The importance of quality control assumes an added dimension because of the mill's remote location, according to Jeffrey M. Shapiro, plant manager. That Great Falls is not a bustling population center is impressed on everyone who works there, he explained. “Our employees know that our customers are a long way from the plant, so it is imperative that we do the job right the first time,” he said. “We ship to urban areas where our competitors have mills. There is a reason they buy from General Mills, and we want to keep it that way.”
The emphasis on quality pervades the entire General Mills corporate culture, said Richard W. Sheldon, director of Gold Medal operations, Minneapolis. “Quality is probably the biggest theme that we pitch to all our mills,” he said. “It's crucial if we are going to differentiate ourselves from the competition. Quality encompasses not only what we do in the mill, but also our ability to find out exactly what the customer needs. And it relates to the importance of working hand-in-hand with the people who buy all our grain.”
Once the decision was made to build the C unit, General Mills faced the challenge of simultaneously renovating the existing mill and building the new unit while sustaining operations at the existing plant.
Ground was broken in October 1996, and a month later walls for the new building were slipformed in six days in temperatures that dipped to minus 16°F. “It was lousy weather, but it's a great building,” Mr. Shapiro said.
Vigen Construction, Grand Forks, North Dakota, U.S., handled the building while Van Sickle, Allen & Associates, Minneapolis, did the architectural engineering. Yellowstone Electric, Billings, Montana, U.S., was in charge of electrical while Industrial Controls, also of Billings, handled the control systems.
Most of the equipment for the new mill was manufactured by Buhler, Inc., Minneapolis, including roll stands (a mix of regular and double highs), purifiers, the high-speed packaging system and the tempering system.
Sifters were supplied by Great Western Manufacturing Co., Leavenworth, Kansas, U.S., including free swinging sifters and, at the finished product area, two in-line sifters.
The Great Falls mill is one of the first in the United States to incorporate the in-line units, said Robert D. Ricklefs, general manager of Great Western. “In-line sifters eliminate supplemental equipment,”
Mr. Ricklefs said. “They can go into a pressure or vacuum conveying line, eliminating the need for additional pneumatic conveying equipment.” Mr. Ricklefs said the Great Falls mill had a history of “pushing the technological envelope.” He said, “Ed Klein (head miller at Great Falls) began automating that mill a long time ago. And they were one of the first plants in the country doing mechanically stretched and glued-on clothing. They were way ahead of the curve.”
Kice Industries, Inc., Wichita, Kansas, U.S., supplied diverter valves and the air stabilization system.
Bulk storage in the B mill was converted to temper bins, and 10 new bulk flour bins were added with a combined capacity of about 900 tonnes, to be utilized by both mill units. The cleaning house was separated from the milling structure and is shared by the B and C units, a feature that Mr. Shapiro said enhances sanitation.
The C mill uses Buhler ingredient feeders with load cells that “apply accurate amounts of enrichment to our flow streams,” Mr. Shapiro said. The system is tied into the computer and can be automatically adjusted as the mill's rate of grind changes.
The highly automated mill uses the Wonderware system of Allen-Bradley, Milwaukee, Wisconsin, U.S. Mechanical installation was handled by Vigen.
The entire milling complex is certified organic by the Organic Crop Improvement Association and produces organic Gold Medal flour in 2.25-kilogram bags. Other organic grades include 22.5-kg bags of whole wheat, high gluten, bread flour and semolina.
Gaining organic certification precludes the use of chemical pesticides or fumigants. Periodic fumigations at Great Falls is conducted using heat, which Mr. Shapiro acknowledges is a greater challenge for the existing B mill than for the new C mill. The B mill was insulated six years ago to eliminate the sanitation issue of condensation on the mill walls that can occur from sub-zero weather that is not uncommon in Great Falls. An added benefit is to help hold the heat in the mill during heat sterilization.
The Kice air stabilization system is used for heat sterilization. The system normally brings in outside air and removes air from every floor to keep temperature and humidity balanced throughout the building. The system also is connected to the plant boilers, and during heat sterilization, the boiler connections are turned on and the flow of air from the outside is cut off, slowly raising the heat above 130°. The process necessitates a four- to five-day shutdown and is performed at least three times a year, Mr. Shapiro said.
“The air stabilization system uses process-generated heat, as required to maintain constant set temperature in the building while the mill is running,” said John E. Kice P.E., vice-president of engineering at Kice. “We provided modulating dampers that are thermostatically controlled to maintain a consistent temperature year around.”
Because the mill cannot utilize even spot fumigations, grain procurement vigilance is crucial, he said. Operators of the truck dump can reject any suspicious loads, he added.
Three classes of wheat are ground at the mill: hard winter, hard spring and durum. Montana origin wheat is primarily ground. The state's wheat tends to have higher protein and fewer quality issues than wheat from other parts of the country, Mr. Shapiro said.
“In my six years here, there have been no crops with quality problems, no vomitoxin,” he said.
In addition to the Buhler loaders, other high-tech features in the mill aimed at optimizing flour quality are on-line monitors located throughout the mill that allow constant gauging of quality. In addition, all personnel are expected to address quality problems. “Operators are empowered to address problems as they occur,” Mr. Shapiro said. “They can shut the mill down if needed.”
A Buhler/Perten on-line N.I.R. analyzer is used to track protein, moisture, color and ash, while a Branscan 1000 provides on-line speck analysis.
The on-line equipment has completely transformed the laboratory function at the mill, Mr. Shapiro said. Rather than testing recent flour and semolina production, the quality engineer's primary function is to see that the various on-line and off-line monitors are properly calibrated.
“The technician is not there to check yesterday's ash,” Mr. Shapiro said. “The laboratory function at the mill is very different from in the past.”
The technician coordinates with the tech center in Minneapolis and works closely with Pacific Northwest grain operations, Mr. Shapiro said.
The C unit is connected to the Pasta Montana plant via a 400-foot pneumatic pipe. While General Mills is committed to providing 100% of the Pasta Montana semolina needs, the unit is shipping product to other customers as well.
The new durum mill produces semolina, granulars, fancy patent and extra fancy patent, Mr. Shapiro said. Pasta Montana purchases all the pure durum products except for the fancy patent, he added.
The mill's new Buhler Futura packaging line has the capability to pack 11.25- and 22.5-kg bags. Gold Medal is packaged in 2.25, 4.5 and 11.25-kg bags. The 22.5-kg bags are for industrial customers, Mr. Shapiro said.
New high-speed bulk loaders allow trucks to be loaded out in only 10 minutes, Mr. Shapiro said.
Describing the start-up of the mill, Mr. Shapiro lightheartedly said that General Mills could make the claim that the unit was the first “lights out” mill in the country, an assertion that several milling companies have made recently. “After start-up, which only took two days, the electricians were still installing lights, and an electrician connected the lighting system to incorrect voltage, and poof! the lighting system for the whole new mill went out,” he said. “We all could have walked around with miner's hats. The mill ran beautifully, but it was definitely lights out.”