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47-595: The Pillsbury A-Mill is a former flour mill located on the east bank of the Mississippi River in Minneapolis, Minnesota . It was the world's largest flour mill for 40 years. Completed in 1881, it was owned by the Pillsbury Company and operated two of the most powerful direct-drive waterwheels ever built, each capable of generating 1,200 horsepower (895 kW ). In 1901 one of the turbines

94-413: A husk. This foundation isolated the building from vibrations coming from the stones and main gearing and also allowed for the easy re-leveling of the foundation to keep the millstones perfectly horizontal. The lower bedstone was placed in an inset in the husk with the upper runner stone above the level of the husk. American inventor Oliver Evans revolutionized the labor-intensive process of early mills at

141-412: A mechanical sieve to refine the flour, or turning a wooden drum to wind up a chain used to hoist sacks of grain to the top of the mill house. The distance between the stones can be varied to produce the grade of flour required; moving the stones closer together produces finer flour. This process, which may be automatic or controlled by the miller, is called tentering . The grain is lifted in sacks onto

188-586: A percentage called the "miller's toll". Early mills in England were almost always built by the local lord of the manor and had the exclusive right (the right of mulcture ) to a proportion on all grain processed in the community. Later, mills were supported by farming communities and the miller received the "miller's toll" in lieu of wages. Most towns and villages had their own mill so that local farmers could easily transport their grain there to be milled. These communities were dependent on their local mill as bread

235-498: A serious fire in 1928. The mill had a good sprinkler system that very likely would have rapidly ended the fire. But the mill was vacant, thus not heated (expensive), and the sprinklers were not functioning. During the late 1990s, the city of Minneapolis, through the Minneapolis Community Development Agency, worked to stabilize the mill ruins. After the city had cleared the rubble and reinforced

282-532: A spark ignited airborne flour dust within the mill, creating an explosion that demolished the Washburn A and killed 14 workers instantly. The ensuing fire resulted in the deaths of four more people, destroyed five other mills, and reduced Minneapolis's milling capacity by one third. Known as the Great Mill Disaster , the explosion made national news and served as a focal point that led to reforms in

329-434: A system that allows the sequential milling of these grists, noting that "a mill, thus constructed, might grind grists in the day time, and do merchant-work at night." Over time, any small, older style flour mill became generally known as a gristmill (as a distinction from large factory flour mills). Modern mills typically use electricity or fossil fuels to spin heavy steel, or cast iron, serrated and flat rollers to separate

376-491: Is a National Historic Landmark . On the outside, the Pillsbury A-Mill is a rectangular structure measuring 175 feet (53 m) by 115 feet (35 m). The foundations are of Platteville limestone . The exterior wall thickness varies from 8'-0" (2.4 m) thick at the basement to 2'-0" (0.6 m) thick at the top of the building. The outside walls are of load-bearing stone with heavy timber framing on

423-442: Is featured throughout the building. Pieces by JoAnn Verburg , Tom Maakestad, Kim Lawler, Kathleen Richert, Paul Wrench and Becky Schurmann include murals, an art glass collage, a 15-foot (4.6 m) Bisquick box, and sculpture. The first Washburn A Mill, built by Cadwallader C. Washburn in 1874, was declared the largest flour mill in the world upon its completion, and contributed to the development of Minneapolis. On May 2, 1878,

470-615: Is probably the Barbegal aqueduct and mill where water with a 19-metre fall drove sixteen water wheels , giving a grinding capacity estimated at 28 tons per day. Water mills seem to have remained in use during the post-Roman period. Manually operated mills utilizing a crank-and-connecting rod were used in the Western Han dynasty . There was an expansion of grist-milling in the Byzantine Empire and Sassanid Persia from

517-755: The Ebro River in Spain is associated with the Real Monasterio de Nuestra Senora de Rueda , built by the Cistercian monks in 1202. The Cistercians were known for their use of this technology in Western Europe in the period 1100 to 1350. Although the terms "gristmill" or "corn mill" can refer to any mill that grinds grain, the terms were used historically for a local mill where farmers brought their own grain and received ground meal or flour, minus

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564-605: The Minnesota Historical Society that opened in 2003, focuses on the founding and growth of Minneapolis, especially flour milling and the other industries that used hydropower from Saint Anthony Falls . The mill complex that the museum is within, dates from the 1870s and is listed on the National Register of Historic Places . It is also part of the St. Anthony Falls Historic District and within

611-508: The Mississippi National River and Recreation Area . The museum features exhibits about the history of Minneapolis, flour milling machinery, a water lab and a baking lab. The centerpiece of the exhibit is the multistory Flour Tower, where visitors sit in the cab of a freight elevator and are taken to different floors of the building, each designed to look like a floor in a working flour mill. Voices of people who worked in

658-483: The Roman Empire by the end of the first century BC, and these were described by Vitruvius . The rotating mill is considered "one of the greatest discoveries of the human race". It was a very physically demanding job for workers, where the slave workers were considered little different from animals, the miseries of which were depicted in iconography and Apuleius ' The Golden Ass . The peak of Roman technology

705-467: The Washburn A Mill , the Pillsbury A-Mill never exploded or caught fire. As a result, it still contains its original wood frame. During the renovation project, a new hydroelectric turbine was installed in a tunnel below the complex. The same tunnel was originally used to mechanically power milling equipment with diverted river water. Due to the significant investment made in sustainable features such as

752-438: The bran and germ from the endosperm . The endosperm is ground to create white flour, which may be recombined with the bran and germ to create whole grain or graham flour . The different milling techniques produce visibly different results, but can be made to produce nutritionally and functionally equivalent output. Stone-ground flour is preferred by many bakers and natural food advocates because of its texture, nutty flavour, and

799-413: The sack floor at the top of the mill on the hoist . The sacks are then emptied into bins, where the grain falls down through a hopper to the millstones on the stone floor below. The flow of grain is regulated by shaking it in a gently sloping trough (the slipper ) from which it falls into a hole in the center of the runner stone. The milled grain (flour) is collected as it emerges through the grooves in

846-488: The " Norse wheel ", as many were found in Scandinavia. The paddle wheel was attached to a shaft which was, in turn, attached to the centre of the millstone called the "runner stone". The turning force produced by the water on the paddles was transferred directly to the runner stone, causing it to grind against a stationary " bed ", a stone of a similar size and shape. This simple arrangement required no gears , but had

893-543: The 3rd century AD onwards, and then the widespread expansion of large-scale factory milling installations across the Islamic world from the 8th century onwards. Geared gristmills were built in the medieval Near East and North Africa , which were used for grinding grain and other seeds to produce meals . Gristmills in the Islamic world were powered by both water and wind. The first wind-powered gristmills were built in

940-592: The 9th and 10th centuries in what are now Afghanistan, Pakistan and Iran. The Egyptian town of Bilbays had a grain-processing factory that produced an estimated 300 tons of flour and grain per day. From the late 10th century onwards, there was an expansion of grist-milling in Northern Europe. In England, the Domesday survey of 1086 gives a precise count of England's water-powered flour mills: there were 5,624, or about one for every 300 inhabitants, and this

987-606: The A-Mill complex as the rebranded East Bank Mills, a loft-style apartment complex containing 759 to 1,095 housing units. However, this redevelopment plan fell through due to financial matters. In 2011, the National Trust for Historic Preservation included the mill on its annual list of 11 Most Endangered Places . In 2013, Twin Cities -based developer Dominium gained approval for a $ 100 million renovation plan to transform

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1034-431: The A-Mill into 251 affordable live/work artist lofts. The exterior of the mill was conserved in order to preserve the historical architecture of the building. However, major changes were made to the interior of the mill and the courtyard behind it. The overall project, which included other buildings within the complex, cost a total $ 175 million. The building was added to the National Register of Historic Places in 1966 and

1081-518: The Washburn A Mill are heard throughout the show. Visitors exit on the 8th floor, where extant equipment is interpreted by staff, and are then led to the ninth-floor observation deck to view St. Anthony Falls. The Gold Medal Flour sign still shines at night atop the adjoining grain elevator. Across the river, the Washburn A Mill's former competitor, the Pillsbury A Mill , is topped with a sign reading "Pillsbury's Best Flour." The work of local artists

1128-901: The belief that it is nutritionally superior and has a better baking quality than steel-roller-milled flour. It is claimed that, as the stones grind relatively slowly, the wheat germ is not exposed to the sort of excessive temperatures that could cause the fat from the germ portion to oxidize and become rancid, which would destroy some of the vitamin content. Stone-milled flour has been found to be relatively high in thiamin, compared to roller-milled flour, especially when milled from hard wheat. Gristmills only grind "clean" grains from which stalks and chaff have previously been removed, but historically some mills also housed equipment for threshing , sorting, and cleaning prior to grinding. Modern mills are usually "merchant mills" that are either privately owned and accept money or trade for milling grains or are owned by corporations that buy unmilled grain and then own

1175-436: The disadvantage that the speed of rotation of the stone was dependent on the volume and flow of water available and was, therefore, only suitable for use in mountainous regions with fast-flowing streams. This dependence on the volume and speed of flow of the water also meant that the speed of rotation of the stone was highly variable and the optimum grinding speed could not always be maintained. Vertical wheels were in use in

1222-654: The end of the eighteenth century when he automated the process of making flour. His inventions included the Elevator, wood or tin buckets on a vertical endless leather belt, used to move grain and flour vertically upward; the Conveyor, a wooden auger to move material horizontally; the Hopper Boy, a device for stirring and cooling the newly ground flour; the Drill, a horizontal elevator with flaps instead of buckets (similar to

1269-553: The fifth floor of the Utility Building (part of the A-Mill complex) while living on the sixth floor, Peter Nelson Hall Architects and his team put together preliminary plans in 1976 that would set in motion the long term vision of the Washburn Crosby Mills as a Minnesota landmark. In 1991 a fire nearly destroyed the old mill. Fires (and explosions) were a well known hazards for flour mills. The A-Mill had

1316-471: The flour produced. One common pest found in flour mills is the Mediterranean flour moth . Moth larvae produce a web-like material that clogs machinery, sometimes causing grain mills to shut down. Washburn A Mill Mill City Museum is located in the ruins of the Washburn "A" Mill next to Mill Ruins Park on the banks of the Mississippi River in Minneapolis . The museum, an entity of

1363-448: The fourth floor held a dust collector, centrifugal machine , gyration shifter, grinder, scale, and a packing bin. The fifth floor held a sifter, separator, and a centrifugal machine. The sixth floor held flour bins and the seventh floor was an electrical room. In 2003, production in the mill ceased and the mill lay empty. The building was then acquired by local developer Shafer Richardson. In 2006 they launched plans to convert and preserve

1410-461: The hydro-electric turbine and a hydrothermal system providing 75% of the building's energy needs, the project achieved LEED Gold Certification in 2017. Flour mill The Greek geographer Strabo reports in his Geography a water-powered grain-mill to have existed near the palace of king Mithradates VI Eupator at Cabira , Asia Minor , before 71 BC. The early mills had horizontal paddle wheels, an arrangement which later became known as

1457-404: The interior (the timber was added after the completion of the building). There are six chimneys on the flat, gravel roof of the building. Due to vibrations of milling machines and poor design, the mill was fortified in 1905. Certain sections were rebuilt in the process. To this day, the walls bow inward 22 inches (560 mm) on the top. Unlike other similarly large mills in the area, most notably

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1504-400: The loose advice of several engineers, carried out the design. Construction started in 1880 and was finished in 1881 under a contractor named George McMullen. The mill was built to put out 5,000 barrels a day at a time when a 500-barrel mill was considered large. Eventually the capacity increased to 17,500 barrels a day. However, for some years the mill was not operated at full capacity. When it

1551-542: The mill's damaged walls, the Minnesota Historical Society announced plans to construct a milling museum and education center within the ruins. Construction on the museum began in March 2001. Designed by Tom Meyer, principal for the architectural firm Meyer, Scherer & Rockcastle, the museum is a new building built with the ruin walls of the 1880 Washburn A Mill. Efforts were made to retain as much of

1598-811: The mill, along with the Pillsbury A Mill and other flour mills powered by St. Anthony Falls , contributed greatly to Minneapolis's development. The mill was designated a National Historic Landmark in 1983 for its technological innovations and its importance in the history of General Mills. Washburn later teamed up with John Crosby to form the Washburn-Crosby Company, which later became General Mills . After World War I , flour production in Minneapolis began to decline as flour milling technology no longer depended on water power. Other cities, such as Buffalo, New York , became more prominent in

1645-404: The milling industry. In order to prevent the buildup of combustible flour dust, ventilation systems and other precautionary devices were installed in mills throughout the country. By 1880 a new Washburn A Mill, designed by Austrian engineer William de la Barre , opened as the largest flour mill in the world, a designation it retained until the Pillsbury A Mill opened across the river in 1881. At

1692-490: The milling industry. Later on in the mill's lifetime, General Mills started putting more emphasis on producing cereals and baking mixes and shifted away from flour milling. The mill was shut down in 1965, along with eight other of the oldest mills operated by General Mills. The Mills were mothballed for several years until the Washburn Crosby Mill was leased to the visionary architect Peter Nelson Hall. Based on

1739-496: The old wheel mills. In most wheel-driven mills, a large gear-wheel called the pit wheel is mounted on the same axle as the water wheel and this drives a smaller gear-wheel, the wallower , on a main driveshaft running vertically from the bottom to the top of the building. This system of gearing ensures that the main shaft turns faster than the water wheel, which typically rotates at around 10 rpm . The millstones themselves turn at around 120 rpm . They are laid one on top of

1786-414: The other. The bottom stone, called the bed , is fixed to the floor, while the top stone, the runner , is mounted on a separate spindle, driven by the main shaft. A wheel called the stone nut connects the runner's spindle to the main shaft, and this can be moved out of the way to disconnect the stone and stop it turning, leaving the main shaft turning to drive other machinery. This might include driving

1833-512: The peak of the Washburn A Mill's production, it could grind over 100 boxcars of wheat into almost two million pounds of flour per day. An ad from the 1870s advertised, "Forty-one Runs of Stone. Capacity, 1,200 Barrels per Day. This is the largest and most complete Mill in the United States, and has not its equal in quantity and quality of machinery for making high and uniform grades of Family Flour in this country." Advertising hyperbole aside,

1880-418: The process. Evans himself did not use the term gristmill to describe his automatic flour mill, which was purpose designed as a merchant mill (he used the more general term "water-mill"). In his book his only reference to "grist" (or "grists") is to the small batches of grain a farmer would bring in to have ground for himself (what would be generally called barter or custom milling). In his book, Evans describes

1927-413: The public that he would build the largest and most advanced flour mill the world had ever seen. He had traveled to mills all over the world, searching for the best technique for milling flour on a large scale. Despite the convention of the time, Pillsbury decided that he wanted his new mill to be designed by an architect in order to make the building visually appealing. Architect LeRoy S. Buffington , with

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1974-416: The runner stone from the outer rim of the stones and is fed down a chute to be collected in sacks on the ground or meal floor. A similar process is used for grains such as wheat to make flour, and for maize to make corn meal . In order to prevent vibrations from the millstones shaking the building apart, they were usually placed on a separate timber foundation, not attached to the mill walls, known as

2021-605: The use of a conveyor but easier to build); and the Descender, an endless strap (leather or flannel) in a trough that is angled downward, the strap helps to move the ground flour in the trough. Most importantly, he integrated these into a single continuous process, the overall design later becoming known as the Automatic (or Automated) mill. In 1790 he received the third Federal patent for his process. In 1795 he published "The Young Mill-Wright and Miller’s Guide" which fully described

2068-522: Was a staple part of the diet. Classical mill designs are usually water-powered , though some are powered by the wind or by livestock. In a watermill a sluice gate is opened to allow water to flow onto, or under, a water wheel to make it turn. In most watermills the water wheel was mounted vertically, i.e., edge-on, in the water, but in some cases horizontally (the tub wheel and so-called Norse wheel ). Later designs incorporated horizontal steel or cast iron turbines and these were sometimes refitted into

2115-527: Was probably typical throughout western and southern Europe. From this time onward, water wheels began to be used for purposes other than grist milling. In England, the number of mills in operation followed population growth, and peaked at around 17,000 by 1300. Limited extant examples of gristmills can be found in Europe from the High Middle Ages . An extant well-preserved waterwheel and gristmill on

2162-698: Was replaced with a 2,500 horsepower one. Both the mill and its headrace tunnel are contributing resources to the St. Anthony Falls Historic District, which is listed on the National Register of Historic Places. The mill is also independently on the NRHP. The mill was named a National Historic Landmark in 1966 and has since been converted into the A-Mill Artist Lofts. In 1879, after five years of secret planning, Charles Alfred Pillsbury announced to

2209-402: Was still in use, the seven floors and the basement of the mill all had specific purposes. The basement held a transformer vault, water inlets, and an electrical room. On the first floor there was a small floor-mounted sifter , a larger ceiling-hung sifter, and a pressure tank . On the second floor there were conveyor belts and a staff lunchroom. The third floor contained more belts and bins and

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