Historic Events, World-Changing Inventions

Shut Up, Frankenstein: Fire GOOD!

Life before man learned to control fire was many things, but mainly it was cold, dark, and perpetually undercooked. The harnessing of fire was perhaps the single greatest turning point in the history of mankind. But just when and where did early human finally learn to make their own fire? The answer lies at least 125,000 years in the past.

Actual photographic evidence of cavemen using fire.

Actual photographic evidence of cavemen using fire.

Come On Baby, Light My…

The earliest existing evidence of mankind—in this case Homo erectus—controlling fire dates back 1.7 million years. These claims are frequently refuted, and the veracity of it kind of depends on one’s definition of “control.” Solid, widely-accepted evidence of mankind’s intentional use, though not necessarily “control”, of fire comes to us from about 400,000 years ago. The earliest supported evidence of mankind for real, for sure, totally on purpose, actively controlling fire has been dated to roughly 125,000 years ago.

This definitive evidence includes burnt animal bones—with human-inflicted cut marks—found at Swartkrans, a National Heritage Site located 20 miles south of Johannesburg, South Africa. Even stronger evidence comes from Zambia’s Kalambo Falls area. Numerous artifacts related to the human use of fire have been found there, including charred logs, charcoal, carbonized plants, and fire-hardened wooden implements. Radiocarbon dating has established the date range of these artifacts as between 61,000 and 110,000 years ago.

Let Me Stand Next to Your…

In Asia, the Qesem Cave archaeological site near Tel-Aviv has yielded evidence of regular fire use that dates back to roughly 382,000 years ago. Evidence discovered in China’s Zhoukoudian cave system points to the use of fire by humans as far back at 460,000 years ago. Burned bones, ash, and charcoal are among the ancient artifacts found in the caves. Testing on the uniformly blackened bones shows characteristics of burning, rather than manganese staining, which could yield a similar visual effect.

I Fell Into A Burning Ring of…

Europe is lousy with evidence of later, but still plenty ancient, humans using fire. The oldest evidence comes from Beeches Pit in Suffolk, England. Uranium series dating—which sounds much more sinister than carbon dating, in an ‘80s to mid-‘90s action movie bad guy kind of way—of the site suggests that mankind utilized fire there as much as 415,000 years ago.

In Hungary, Spain, and elsewhere, various artifacts and evidence point to mankind harnessing fire around 350,000 years ago. Stone hearths found in France have been dated to 200,000 years ago, suggesting that humans of that time period had greatly advanced their control of fire and had truly made it their b!+©#.

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Historic Events

The Washburn A Mill Explosion of 1878

The Washburn A Mill was a flour mill in Minneapolis, Minnesota. Built in 1874 under the direction of the excellently-named Cadwallader C. Washburn, it was frequently touted as being the world’s largest flour mill, though the claim may or may not be true. No one officially kept track of that kind of thing back then, as people generally had better things to do.

The facility was almost completely destroyed by an explosion in the spring of 1878.

Early Minneapolis Landmark Goes BOOM!

Washburn A Mill’s flour grinding equipment was powered by the flow of water down St. Anthony Falls on the Mississippi River, located in what is now the heart of Minneapolis. The mill’s incredible milling capacity—it was also claimed that the mill could grind more than 100 train boxcars’ worth of wheat into roughly 2 million pounds of flour every day—contributed to Minneapolis’ significant growth during the late 19th century.

Photo credit: Internet Archive Book Images via Foter.com / No known copyright restrictions

Photo credit: Internet Archive Book Images via Foter.com / No known copyright restrictions

On 2 May 1878, a spark of unknown origin ignited the dense flour dust within the mill, causing a massive explosion and ensuing fire. The mill itself was all but leveled in the explosion; at least eighteen mill workers were killed instantly. The fire raged out of control and destroyed five neighboring mills. The Great Mill Disaster, as it came to be known, reduced Minneapolis’ considerable milling capacity by a third.

As was the norm at the time, Washburn A Mill had no interior ventilation system in place to minimize dust explosion risk. The phenomenon was not unknown at the time, as similar accidents had occurred at other, smaller mills around the world. However, the destruction of such a large and well-known facility became a major national news story, and ultimately led to numerous safety reforms in the milling industry.

After the Tragedy

A new (and improved) Washburn A Mill was built on the site and completed in 1880. Designed by Austrian engineer William de la Barre, the new mill was, once again, said to be the largest in the world—advertisements boasted: “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.”

The new mill put Minneapolis’ milling industry back on track, and helped the city continue its growth into the new century. Washburn (the guy, not the mill) joined forces with John Crosby soon after, forming what is now General Mills. The mill was finally shuttered in 1965, after decades of reduced production and General Mills’ increased emphasis on cereals and baking mixes rather than straight flour.

The Washburn A Mill site today. Photo credit: amee@work via Foter.com / CC BY-NC-ND

The Washburn A Mill site today.
Photo credit: amee@work via Foter.com / CC BY-NC-ND

The disused Washburn A Mill was nearly destroyed by fire in 1991. Soon after, however, the Minneapolis Community Development Agency announced plans to stabilize the ruins, partially rebuild the mill, and turn it into what is now the Mill City Museum.

Historic Events

The 2008 Georgia Sugar Factory Explosion

At approximately 7:00pm on February 7, 2008, a massive dust explosion shook the Imperial Sugar refinery in Port Wentworth, Georgia. The explosion killed 14, injured 42, and destroyed 12 percent of the 872,000 square foot facility. OSHA investigations of the event found that the explosion had been “entirely preventable.” The disaster led to the development of new technology designed to prevent future combustible dust explosions in similar situations.

Background: The Dixie Crystals Refinery

The sugar processing plant, known as the Dixie Crystals Refinery, was built in 1916, opened a year later, and had been in operation almost continuously since then. Constructed on a 160 acre site, the facility was the second largest sugar refinery in the United States. Sugar Land, Texas-based Imperial Sugar bought the factory from the previous, local owner. In 2007, the facility refined roughly nine percent of all the sugar used in the US that year, making it one of the highest-producing sugar refineries in the world.

Dixie Crystals

Many areas of the factory had never been fully updated or renovated, and still contained the now-outdated construction methods and materials used in the plant’s initial construction. The facility’s ceilings were made of wood; creosote tar was still plentiful, despite being a well-known fire risk.

In 2005, after three similar and fatal explosions two years prior, the US Chemical Safety and Hazard Investigation Board (CSB) had released the findings of a study that investigated the risks of combustible dust explosions. The report stated that dust explosions posed a severe risk, with evidence showing that 281 combustible dust explosions had occurred in the US between 1980 and 2005. The CSB subsequently made numerous recommendations to the Occupational Safety and Health Administration (OSHA), only some of which had been implemented by 2008.

The Explosion

The explosion occurred at roughly 7pm, erupting from the center of the Dixie Crystals Refinery, in a building where processed sugar was fed to storage and bagging equipment via a series of conveyor belts and elevators. One-hundred-twelve employees were onsite at the at the time, including Imperial Sugar CEO John Sheptor.

Sheptor, who survived the blast only because he was protected by a firewall, stated that the accumulated dust from countless tons of processed sugar had acted like gunpowder. Sugar dust, a highly combustible substance, would be officially identified as the fuel for the explosion within 24 hours of the explosion. Evidence suggests that a spark, caused by equipment that was overheating due to the significant accumulated buildup of sugar dust along the conveyor line, served as the source of ignition.

The building at the event’s epicenter was destroyed in the explosion and ensuing fire, as were several others nearby. Two 100-foot tall, reinforced concrete storage silos adjacent to the building caught fire, as well, and the sugar inside the silos continued to burn and smolder for seven days before finally being extinguished. Over 3 million pounds of fire-hardened sugar were eventually recovered from the silos.

Ambulances from 12 counties and fire fighters from three responded, as the US Coast Guard, which closed off a portion of the Savannah River alongside the refinery.

OSHA & CSB Investigate

OSHA arrived on the scene within two hours. An OSHA investigation was launched immediately, as well as an independent CSB investigation. Interviews with employees of the refinery revealed a lack of training and preparedness—40 of those interviewed had never received training on exiting the building in an emergency, and only five recalled any instance of a fire drill having been conducted.

Less than a month later, OSHA sent a letter to 30,000 employees across the US, altering them to the danger of dust explosions in the workplace. A Congressional bill was soon proposed by OSHA as well; the Combustible Dust Explosion and Fire Prevention Act of 2008 was passed by the House of Representatives, but stalled out in the Senate. Numerous new OSHA regulations were enacted in the wake of the Dixie Crystals Refinery dust explosion.

The CSB completed their investigation the next year, and released their report in September 2009. In it, the explosion was called “entirely preventable.” CSB investigators noted that companies in all areas of the sugar industry had been well aware of the potential for combustible dust explosions since 1926, citing memos from the late 1960s that voiced concerns about these risks. The CSB also revealed that Imperial Sugar’s own construction changes on the site had exacerbated the accumulation of sugar dust, and that the company had never practiced evacuation procedures.

From Disaster Springs Innovation

Following the Dixie Crystals Refinery dust explosion, equipment manufacturers for the sugar processing and the broader chemical processing industry set out to develop new ways to reduce or eliminate the risk of combustible dust explosions. As the Georgia plant’s conveyor system was identified as the source of ignition, a good deal of these efforts were focused on improving material conveyors.

The first step was safer, more efficient conveyors that utilized fewer moving parts, thus reducing friction and heat generation. From there, industry engineers went on to develop pneumatic conveyor systems that can transport materials with almost no friction and that significantly reduce the creation of material dust.

Currently, the most advanced solution yet for preventing combustible dust explosion is being developed by Nol-Tec Systems in partnership with Air Products and Chemicals. This new system will incorporate a state-of-the-art pneumatic conveyor, and, for further improved safety, will replace the combustible system’s oxygen flow with an inert gas. This inert gas will not operate in a vacuum, but rather will be pumped through the system in high enough quantities to displace oxygen down to a non-combustible level—less than 15 percent of the volume of the conveying flow.

The two companies co-authored a related research paper, “Prevent Combustible Dust Explosions with Nitrogen Inerting”, in the March 2015 issue of Chemical Engineering.

Photo credit: Scott McLeod / Foter / CC BY