The Steffen House – A molasses desugarization effort that failed to gain traction
What happened to Steffen House, once a critical feature of beet sugar factories, especially in Europe? A Steffen House was considered so essential to the economic success of a beet sugar factory that a major player in the business of building and operating beet sugar factories in the early days of the 20th century, Henry Oxnard, said no. he would accept a contract to build a sugar factory unless it included a Steffen House.
A key performance measure of a beet factory then and now is the percentage of sucrose in the molasses. The appearance of any sucrose in the molasses is evidence that the sugar destined for storage ended up in the molasses instead. In Oxnard’s day, molasses was considered a waste product and as such was often dumped into rivers adjacent to a sugar factory. Typically, in a standard factory lacking a Steffen House, or in this more modern period, an ion-exchange process, beet molasses will consist of fifty percent sucrose, an unacceptable loss to those engaged in management. of a beet factory. Factory superintendents refer to the presence of sugar in molasses as “purity.” So, high purities reflect high sugar losses in the molasses, the same as throwing money down the drain.
Molasses production is generally equal to five percent of the processed beet, so a production of 1,000,000 tons of beet could result in the production of 50,000 tons of molasses containing approximately 25,000 tons of sugar which would have a value ten million dollar market. assuming sugar sells for $0.20 per pound, net of manufacturing costs. It goes without saying that preventing loss of sugar in molasses is a primary challenge for beet factory managers. From the beginning, the technology captured as much sugar as the existing equipment allowed at the time, the next curative was to remove the sugar from the molasses. That became the role of Steffen House.
The Steffen process was a method of extracting sugar from molasses invented by Carl Steffen, a Vienna-born Austrian who patented the process in 1883 while engaged in sugar manufacturing in Moravia. Although his method has several variations, the process basically begins by diluting the molasses with water (enough to create a 5-12% sucrose solution) and cooling it to a very low temperature (below 18°C), after whereby finely pulverized lime (calcium oxide) in sufficient quantity to establish a ratio of 130 percent to the sucrose content is added continuously with stirring at a slow uniform rate. The sugar in the molasses combines with the lime, forming a saccharate of lime that is insoluble in the liquid. The sucrose was then separated and washed in a filter press. The filter press cake (saccharate of lime) was mixed with fresh water to a creamy consistency and took the place of milk of lime in the carbonation process.
About ninety percent of the sugar originally contained in beets was extracted in those factories that used the Steffen process. In some facilities, the wastewater from the Steffen process, rich in fertilizing qualities (mainly potassium sulfate), was used to irrigate land adjacent to the factory. The structure designed to accommodate the equipment used in the Steffen process was generally referred to in the industry as the “House of Steffen”.
The Steffen process quickly gained popularity in Europe, but found less acceptance in the United States, probably because the process was more sophisticated in terms of its associated chemistry than any process introduced in a beet factory up to that time. The first such process was installed in 1888 in Watsonville, California. It was a small pilot plant with three 5ft chillers supplied by the Grevenbroich Machinery Company of Germany. Grevenbroich eventually supplied much of the equipment for three pioneering California factories, Watsonville, Los Alamitos, and Chino, and continued to supply Oxnard’s Steffen process equipment until his company and Kilby Manufacturing of Cleveland, Ohio, began producing improved models a few years later. later.
In the United States, the list of accomplished chemists who held leadership positions in beet factories was slim. Factory superintendents often stuck to the tried and true technology of the past, preferring methods learned from experience rather than scholarship. Guided by practical experience rather than theory, they would uncritically reject ideas and methods for which they lacked a basis for understanding. The Watsonville experimental Steffens process was little used, for example, because the factory superintendent “didn’t believe in it.”
The main attraction of the Steffen process was its comparative advantage. Molasses was then an unwanted product and was presented more as a waste problem than as a salable product. Extracting sugar from molasses was seen as getting good value for something that would otherwise be dumped into the river, a practice that, from the earliest days of the US beet industry, was wrong. seen by those who depended on the rivers for other industrial purposes, including fishing. Over time, the molasses, which is basically a sugar syrup that has been through the factory several times and, through the removal process, is mainly sugar beet residue containing fifty percent sucrose, found a variety of markets. At first, it became a source of ethyl alcohol, but it fell out of favor for many years due to the low cost of foreign crude oil. Interest in ethyl alcohol production would revive in the 1970s when crude oil prices increased. Molasses is also a main raw material for the production of baker’s yeast and is an important source for the production of monosodium glutamate (MSG) and citric acid. However, the volume demanded by these users was low compared to the amount made available by the country’s beet sugar companies. As a consequence, the price of molasses was low.
In the 1970s, attitudes toward factory waste changed from acceptance by the general public to almost total rejection of the premise that because factories are good (they provide useful products and economic strength), their waste must be tolerated. Therefore, the Steffens process, which produced liquid wastes with high alkalinity and pH, as well as high organic content and consequent malodorous compounds, was not well received. One Steffens House discharged wastewater in amounts up to 800 percent of the volume of molasses processed.
Several studies indicated that it was possible to improve the intensity of odors emanating from Steffen waste. However, the cost of installing and operating effective systems would outweigh the economic gains provided by the process. Thus, the managers of the factories that used the Steffens process began to close them down, and those who wanted the benefits of the Steffens process looked elsewhere. Adding to its shortcomings on the environmental front, the Steffens process recovered only about 60% of the sugar in the molasses. Sugar manufacturers began to look elsewhere for a solution to the task of recovering sugar from molasses. Seeping into his thoughts was the idea that it would be best to avoid making molasses in the first place. They turned to ion exchange, a process that would avoid making molasses in the traditional sense.
Ion exchange, or deionization, is a method of reducing impurities from the juice which then allows for further sugar extraction. The principle of ion exchange has been known for over 125 years, but is rarely used in the beet sugar industry due to its unfortunate habit of increasing the sodium content of sugar juices, which retards crystallization ability. of sugar. However, today’s sugar manufacturers turned to the practice of ion exclusion chromatography, which was first used successfully to produce high-fructose corn syrup (HFCS). The process is based on the exclusion of ionic compounds and the inclusion of non-ionic compounds.
Molasses, then, once regarded as a thief that captured large volumes of valuable sugar during the sugar manufacturing process, was ultimately forced to deliver its loot via ion exchange where sugar recovery rates reach ninety percent. percent compared to sixty percent in the process. former Steffens House and no negative environmental impact. And another bonus awaited the sugar factories that turned to ion exchange.
Modern factories starting in the 1990s began producing betaine from molasses, a valuable food additive with additional medicinal benefits. The University of Maryland Medical Center noted in one of its studies that inexpensive wines that use beet sugar to increase alcohol content contain betaine. Some experts suggest this may explain why French wine drinkers tend to have low rates of heart disease despite diets high in fat and cholesterol. More convincing, however, is the value of betaine as a feed supplement for chickens and pigs. Several experiments show that the addition of betaine to food improves performance. Furthermore, studies with pigs indicate an effect of betaine on energy metabolism and a strong increase in growth hormones. Humans are also finding uses for betaine as a food supplement under a different name, trimethylglycine, or TMG.
Thus, the Steffen process, once the savior of sugar manufactures, fell into disrepute due to cost and environmental concerns, but gave way to more efficient and environmentally friendly ion exchange.
Sources:
GREAT WESTERN SUGAR COMPANY, The Technology of Beet Sugar Manufacture, The Great Western Sugar Company, Denver, Colorado, June 30, 1920: an instruction manual prepared in large part by DJ Roach for use by operating employees of sugar factories company’s beet.
GUTLEBEN, Dan, The Sugar Tramp-1954- Michigan, Printed by: Bay City Duplicating Co, San Francisco, 1954
McGINNIS, RA (Ed.) 1982, Beet Sugar Technology, Fort Collins, Colorado, Beet Sugar Development Foundation