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Chemical Industry Digest- May 18

Chemical Industry Digest
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Chemical Industry Digest- May 18

Articles covered in this issue:

Process Intensification Opportunities in Multiphase Stirred Tank Reactors
Manishkumar D. Yadav, Gaurav G. Dastane, Chandrakant R. Holkar, Aniruddha B. Pandit, Institute of Chemical Technology, Mumbai; and Shankar B. Kausley, Tata Consultancy Services Ltd.
In this article, an overview of process intensification in stirred tank reactors leads to many opportunities to enhance productivities. An overview is presented along with their industrial applications. Design aspects are also discussed.

Tiny Reactors – Aim for a big role
Rocky Costello, R. C. Costello & Associates, Inc
In this article, the author emphasizes on how process intensification has improved the reactor technology with different examples.

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Chemingineering | Managing Water

K. Sahasranaman (Independent Industry Consultant)
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Chemingineering | Managing Water

 

In this month’s column, Sahasranaman builds a case for compulsory water audit along the lines of the energy audit. It would bring the necessary discipline in the industry to survive the increasingly water-stressed times. The 3R principle of Reduce – Reuse – Recycle has to be widely adopted by the industry to manage water. In the long term, industry and agriculture need to partner for a holistic management of water.

No other month reminds us more about water in India than May. The hardest hit is our thermal power plants, many of which are located in highly water-stressed areas. They are forced to operate at part loads or even shut down. The latest data released by Central Water Commission is cause for alarm. The average live water storage of all of our water reservoirs have shrunk to a low of 20%.

Industry accounts for 19% of fresh water usage globally, while agriculture and households use 69% and 12% respectively. But this does not tell the whole story. Agriculture is now using 3 times more water than 50 years ago and this is expected to increase by 19% by 2050. Since food has to be the top priority, the industry will be under increasing water stress in the coming years. With 18% of global population and only 4% of the global water, India’s situation is extremely precarious. Indian agriculture consumes as much as 87% of water with industry accounting for 8%. Industry gets the last priority in our National Water Policy and thus suffers most even though it accounts for only 8%. It is no secret that our agriculture is wasteful in its water usage. But unless there is a strong political will, the industry will continue to bear the brunt of water scarcity.

Water in Industry

Among industry, thermal power plants are the biggest consumers with a whopping share of 88%. Other water guzzling industries are engineering, pulp and paper, textiles, steel and sugar. When benchmarked globally on water usage, Indian industries come across as very inefficient. There is thus scope for conserving water through process modifications and better operating practices.

The biggest usage of water by industry is for cooling, most of which is lost to the atmosphere by evaporation. Next comes raising steam. Water is used in product purification, as a solvent or for washing. Water is also used for producing the vacuum. In addition, water also sometimes form part of the product, either as a diluent or by participating in the chemical reaction.

Managing freshwater requires the application of the 3R (Reduce – Reuse – Recycle) principle:
• Process changes to reduce water demand
• Reuse of wastewater from one process in another process.
• Recycle of wastewater in the same process.

Reduce

Water usage can be reduced through process modification and re-engineering. Cooling loads can be minimised by applying pinch technology to increase process to process heat exchange. Heat pumps can reduce cooling loads of distillation columns. Major cooling loads can be transferred to air, keeping only a small residual load for cooling water. Water make-up to closed cooling water circuits can be reduced by operating at higher concentration cycles and adopting better water treatment methods.

Upgrading water-ring vacuum pumps to the expensive dry vacuum pumps reduce water and wastewater.

Washing and rinsing operations consume a lot of water that ends up as wastewater. The efficiency of washing can be increased by providing turbulence, either through spraying or air agitation. Increased contact time in multistage washing also improves efficiency. A countercurrent multistage washing system can reduce water consumption by as much as 90% compared to a single-stage process.

Water is purified either through ion-exchange or Reverse Osmosis, and there is a loss of water in both process. By choosing better ion-exchange resins and improved column design, washing and rinsing cycles can be reduced to save water. Improved RO membranes increase recovery and reduce water lost in rejects.

The major impediment to implementing most of these measures is that they do not yield decent payback and that is because water is not realistically priced.

Pinch Technology

Much of the water used in industry ends up as effluent. Reuse and recycling of wastewater not only reduces fresh water usage but also reduces the effluent disposal problems. Opportunities for water reuse and recycle are not easy to spot, especially in large chemical plants. Pinch technology, which has been extensively used for heat integration in large process plants, can also be used to discover possibilities of water reuse and recycle. Using pinch techniques fresh water requirement can be matched with treated recycle water.

Levels of treatment can be matched with fresh water specifications to reduce costs.
Treating wastewater for reuse and recycle is not always easy. Some contaminants are intransigent and difficult to biodegrade. Technology licensors mostly shy away from offering guarantees on effluent quality and quantity, especially for new technologies that haven’t fully matured. Also, operators treat wastewater guarantees lackadaisically compared to energy consumption for example. They are often willing to let go of the shortfall in wastewater guarantees and manage it by diluting with clean water as long as the licensor picks up the tab.

Water Audit

There is a strong case for water audit along the lines of the energy audit. Unlike energy, the demand-supply equation doesn’t seem to govern water pricing. Most people refuse to even consider it as a commodity and treat it as a gift of nature. Water audit will change this perception in a big way. The principle behind water auditing is – if you don’t measure it, you can’t manage it. The audit will require companies to measure water used at every point and trace where it ends up. Water balance will reveal how and where water is lost.
Water audit will have to be made compulsory for designated industries. This will require an act of parliament to establish a body similar to the Bureau of Energy Efficiency. Industries will have to employ certified water managers. They will have to also get a water audit done annually by a certified water auditor and demonstrate continuous improvement. This will promote benchmarking of water consumption. Compulsory water audit will bring the required discipline in the industry.

The long-term vision of industry should be to lobby with the authorities to get it an even footing as agriculture in the National Policy. Agriculture can easily save water by adopting practices like drip irrigation, which is however capital-intensive. As part of their CSR, big industries can adopt farms in their taluka or district and implement such water conservation methods. Such collaboration between industry and agriculture is the need of the hour.

It is unrealistic to expect dramatic savings from water management. Improvements in the industry would be incremental, but as the saying goes little drops of water make the mighty ocean.

Readers’ responses may be sent to k.sahasranaman@gmail.com or chemindigest@gmail.com

Peter Debye(1884 – 1966)- Phenomenal Achievements in Physical Chemistry

Veena Patwardhan
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Peter Debye(1884 – 1966)- Phenomenal Achievements in Physical Chemistry

When the Dutch physicist and physical chemist Petrus Debye first arrived from Europe at Cornell University, Ithaca, New York, in 1939-1940 to deliver the Baker lectures in Chemistry, he was 55 years old, already a Nobel Laureate, and acknowledged as one of the greatest scientists of the twentieth century. He had been awarded the Nobel Prize in Chemistry for his contributions to the study of molecular structure through his investigations on dipole moments and on the diffraction of X-rays and electrons in gases.

After coming to the US, he accepted the position of Professor of Chemistry and Principal of the Chemistry Department of Cornell University in 1940 and took American citizenship in 1946. On retiring from this post in 1952, he was appointed as Emeritus Professor of Chemistry at Cornell.

Peter Debye, as he now came to be called, had achieved such a towering stature as a physical chemist internationally, that the American Chemical Society decided to name its annual award for an outstanding physical chemist as the ‘Peter Debye Award in Physical Chemistry’. In a tribute to him after he died, F. A. Long, the Vice-President and Professor of Chemistry at Cornell University said Peter Debye’s influence on the Cornell Chemistry Department and on Chemistry in the US was profound. It wouldn’t be too far-fetched to accept that his influence on chemistry in the world to has been immense.

Early education and distinguished academic career in Europe

Petrus (Peter) Josephus Wilhelmus Debye was born at Maastricht in the Netherlands on March 24, 1884. He completed his early education at the elementary and secondary schools in his hometown, and in 1901, joined the Aachen University of Technology, focusing on the study of mathematics and classical physics. In 1905, he completed his degree in electrical engineering, and two years later, published his first paper – a significant mathematical solution to a problem involving eddy currents. While at Aachen, he studied under the celebrated theoretical physicist Arnold Sommerfeld, who later openly referred to Peter Debye as his most important discovery.

In 1906, when Sommerfeld received an appointment at Munich, he took Debye along with him as his assistant in theoretical physics. In 1908, Debye got his Ph.D. in Physics with a dissertation on radiation pressure and thereafter qualified as a University lecturer in 1910. That same year, he derived the Planck radiation formula coming up with a method that even Max Planck agreed was simpler than his own.

In 1911, Debye took up the professorship at the University of Zurich, Switzerland that Albert Einstein vacated on joining the German Charles-Ferdinand University in Prague. After that, he changed universities every few years. He returned to the Netherlands as Professor of Theoretical Physics at Utrecht University in 1912, then moved to Göttingen, Germany in 1913 to lecture in experimental physics, thereafter to the Swiss Federal Institute of Technology (ETH), Zurich in 1920 as the Principal of the Institute and Professor of Physics, and then to the University of Leipzig, Germany in 1927 where he held a similar position. In 1934, he succeeded Einstein as the Director of the Kaiser Wilhelm Institute for Physics (now called the Max Planck Institute) in Berlin and was also Professor of Physics at the University of Berlin. From 1937 to 1939 he served as the President of the German Physical Society (DPG). The positions he held from 1934 to 1939 were during the years that Adolf Hitler ruled Nazi Germany.

Interestingly, despite his recurrent appointments as a theoretical physicist, Debye had also spent several years lecturing on experimental physics at Göttingen. It is believed that his close association with the experimental physicist Max Vien while studying at Aachen University helped him excel in experimental physics as well in later years. His last appointment was in the US at Cornell University where he continued engaging in research work till he died.

Remarkable scientist, brilliant teacher

The earliest of Debye’s several major scientific contributions was in 1912 when he developed equations to calculate the size of the molecular dipole moments and also determined information regarding the structure of molecules. The measurement of dipole moments plays a significant role in understanding the nature of the chemical bonds between the atoms in a molecule, distinguishing between polar and non-polar molecules, and determining the shapes of molecules. Debye’s work on the measurement of molecular dipole moments was so crucial that the units for these measurements are named Debye Units after him.

In 1912, the same year in which he studied the concept of dipole moments, Debye developed the Debye model for vibrations of atoms in solids extending Albert Einstein’s theory of specific heat to lower temperatures by including contributions from low-frequency phonons. In 1913, he extended Niels Bohr’s theory of atomic structure by introducing elliptical orbits. In plasma physics and colloid chemistry, the Debye length is defined as the distance over which mobile charge carriers such as electrons screen out electric fields. In 1923, together with his assistant Erich Hückel, he developed the Debye-Hückel theory of electrolytic solutions, an improvement over Svante Arrhenius’ theory of electrical conductivity in electrolyte solutions. In 1923, Peter Debye also developed a theory to explain the Compton Effect, named after American physicist Arthur Compton, discovering independently that collision with electrons causes the wavelength of X-rays to increase. All of these contributions bearing Debye’s name are significant extensions of the models proposed earlier by major scientists.

As a teacher, Debye’s devotion to his students and science was unmistakable. He was always courteous and friendly and always happy to discuss an interesting new idea with his students or visitors. He could as easily explain complex scientific ideas to school children as to his colleagues. F. A. Long, who was a freshly appointed assistant professor when Peter Debye first came to Cornell University had also written this in his tribute: ‘Those (Debye’s) lectures were lively, vigorous, and filled with that sense of intellectual excitement which I came to realise was a Debye hallmark.’ He said Debye’s lectures were greeted with much enthusiasm and that the Cornell faculty were overjoyed when he accepted the offer to stay on as Professor and Chairman of the Chemistry Department.

It is believed that the pressure from Hitler’s government to give up his Dutch nationality had made Debye decide to try to move to the US. A lot of his work at Cornell involved the use of light-scattering techniques, following on his X-ray scattering work done years earlier, for determining the size and weight of polymer molecules. When World War II broke out synthetic rubbers had been invented but it was essential to know their molecular weight. This was made possible by Debye’s research during the war on small angle light scattering. This research was later extended to include the study of proteins and macromolecules.

Unfortunate controversy

A book in Dutch by the Dutch writer-scientist Sybe Rispens published in 2006 insinuated that Peter Debye was a Nazi sympathiser who had removed several Jewish employees from the Kaiser Wilhelm Society during his directorship and as President of DPG and even signed off his letters with ‘Heil Hitler’. However, several in-depth investigations carried out subsequently in the Netherlands and the US revealed that Debye was apolitical. The earliest of these carried out by the Cornell University’s Department of Chemistry and Chemical Biology issued a report in May 2006 that states:

Based on the information to-date, we have not found evidence supporting the accusations that Debye was a Nazi sympathizer or collaborator or that he held anti-Semitic views. It is important that this is stated clearly since these are the most serious allegations.

Even decades before Rispens, several writers had clearly mentioned Debye’s staunch resistance to Nazi activities. Many scientists and scholars have pointed out that the DPG had succeeded in retaining their threatened Jewish staff as long as possible despite increasing pressure from the Nazis, and that as a civil servant, even Max von Laue, a leading opponent of the Nazis was obliged to sign letters with ‘Heil Hitler’. Besides, the help Debye and his colleagues extended at great risk to themselves and their families to their Jewish colleague Lise Meitner to cross the Dutch-German border and go to Sweden to escape Nazi persecution is well documented.

Others point out that when Debye received the Max Planck medal of the DPG in 1950, nobody, not even Einstein, Max von Laue, and other Jewish scientists who knew Debye closely, objected.

Awards and recognition galore

The honours bestowed on this outstanding scientist are too many to list here, running into scores, some of the prominent ones being the Nobel Prize in 1936, the Rumford Medal of the Royal Society, London in 1930, the Lorentz Medal of the Royal Netherlands Academy in 1935, London, the Max Planck Medal in 1950 by the West Germany Physical Society, and the Priestley Medal of the American Chemical Society in 1963.

Debye was a Visiting Lecturer at universities across the US and Europe and associated with numerous scientific academies across the world including the Indian Academy, Bengaluru, and the National Institute of Science in India.

We owe a number of the concepts in chemistry that we often take for granted today to Debye who proved these after meticulous experimental measurements. His passion for scientific work never flagged until the end. He died of a heart attack on 2 November 1966 at the age of 82 and is buried in the Pleasant Grove Cemetery at Ithaca, New York.

References

  1. Nobelprize.org: Peter Debye – Biographical – Nobel Media AB 2014 – https://www.nobelprize.org/nobel_prizes/chemistry/laureates/1936/debye-bio.html
  2. Elangannan Arunan: Peter Debye – Resonance, December 2010, Indian Academy of Sciences.
  3. FamousScientists.org: Peter Debye – https://www.famousscientists.org/peter-debye/
  4. F. A. Long: Peter Debye – An Appreciation – Science, 24 Feb, 1967: 979-980.
  5. European Synchrotron Radiation Facility: Historical Notes on Peter Debye.
  6. http://www.esrf.eu/UsersAndScience/Experiments/CRG/BM26/SaxsWaxs/Debye.
  7. ChemViews: 50th Anniversary: Death of Peter Debye – ChemViews Magazine, 02 November 2016.

Lithium – Powering today’s technology

Veena Patwardhan
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Lithium – Powering today’s technology

Once an element with limited known uses, today lithium, the first metal of the periodic table and also its lightest metal (density around half that of water), plays a key role in the lives of people worldwide. Ever since the German-born American professor John Goodenough developed the Lithium-ion rechargeable battery in the 1980s, the demand for lithium has been growing by leaps and bounds.

In 2014, analysts declared the demand was rising by around 12% annually. Not surprising, given that any portable device you pick, chances are it runs on a lithium-ion battery. Clearly, the lightest metal on earth is no longer a lightweight.

Discovery of lithium

In the 2nd century AD, the Greek physician Soranus had written about the curative properties of the mineral-rich waters of his hometown Ephesus, then a Greek city, for promoting mental health. He advocated that patients suffering from mania and melancholia soak in the waters of these springs. We now know that these waters have high levels of lithium salts. The ancient Greeks like Soranus had neither isolated nor identified lithium, but they had discovered the link between the waters of mineral springs rich in lithium and the treatment of manic patients.

The first lithium mineral, petalite, was discovered around 1800 on the Swedish island of Utö by the Brazilian chemist and statesman José Bonifácio de Andrada e Silva.

In 1817, a 25-year old Swedish aristocrat and chemist Johan August Arfvedson, while analysing petalite ore in Berzelius’s private lab in Stockholm, realised he had stumbled upon a new element. He subsequently detected the same material in the minerals spodumene and lepidolite as well. Arfvedson found that the new element formed compounds similar to those of sodium and potassium, but that its carbonate and hydroxide were less soluble in water and more alkaline. The new element was named lithium, a name derived from ‘lithos’, the Greek word for stone, signifying that it had been discovered in a solid mineral, unlike other common alkali metals that had been discovered in plant material.

In 1818, the German chemist Christian Gmelin was the first to observe that lithium salts impart a bright red colour to a flame. Both Arfvedson and Gmelin made several attempts to separate lithium from its salts but failed. In 1821, the English chemist William Thomas Brande succeeded in isolating a small quantity of lithium by the electrolysis of lithium oxide, a process Sir Humphrey Davy had previously used for isolating the alkali metals potassium and sodium. Today, we know that lithium is toxic in larger quantities and corrosive too. But this was not known to the first scientists attempting to study it. Indicative of the times when scientists were not very vigilant or not overly concerned regarding their safety, in his book A Manual of Chemistry, Brande had written: “Pure lithia (lithium oxide) is very soluble in water, and its solution tastes acrid like the other fixed alcalis.” He also mentioned that the element lithium had not yet been investigated because of a difficulty in procuring an adequate quantity of its oxide.

In 1855, Robert Bunsen and Augustus Matthiessen produced sufficiently larger quantities of lithium through the electrolysis of lithium chloride. This paved the way for the commercial production of lithium in 1923 by the German company Metallgesellschaft AG, through the electrolysis of a liquid mixture of lithium chloride and potassium chloride.

A soft, silvery metal lighter than any other, lithium floats on oil and water. But attempting to float it in water would be a disaster, for like other alkali metals it reacts vigorously with water, even moisture in the air, producing immense heat, and even bursting into flames. Lithium is therefore stored by covering it completely in mineral oil, petroleum jelly, or any other non-reactive liquid. Its high reactivity is one reason why some lithium-ion batteries catch fire or explode at high temperatures.

Availability in nature

Lithium is a relatively rare metal present in a concentration of around 20 parts per million (ppm) in the earth’s crust, around 0.17 ppm in the oceans and in trace amounts in the atmosphere, the food we eat, and in our body. Being highly reactive, it is not found in the metallic, elemental state in nature, but rather in the form of compounds in minute amounts in igneous rocks and in the waters of many mineral springs. The major minerals containing lithium include spodumene, petalite, lepidolite, and amblygonite.

Traditionally, lithium is extracted from brine pools or mined from hard rocks. The latter is a time-consuming, energy-intensive and costly process for a lot of rock has to be dug out of the earth to get a small amount of lithium. The more economical and efficient way is by concentrating huge brine pools through solar evaporation. Lithium is then produced by the electrolysis of molten lithium chloride and potassium chloride. In Chile, Argentina, China, Russia, and the US, they use the brine-based extraction method.

The brines, that are volcanic in origin, are found in high altitude desert regions in the form of playas (where the basin surface mainly comprises silts and clays and the brine is underneath) or salars (salt lakes or salt flats where the surface is predominantly salt). Most of the world’s lithium production takes place in South America. The largest brine pool in the world is the salt flat in Bolivia called the Salar de Uyuni. A fascinating tourist attraction, it sits at a height of around 3653m and extends over 12,000 sq. km. and is believed to be one of the most awe-inspiring sights in South America.

Varied applications: Some flawed, others favourable

From around the mid-1800s, lithium-rich spa waters were recommended as a popular cure for gout, till this was proved to be more harmful than beneficial in 1912.

In the late 1940s, lithium chloride was sold as a salt substitute for people who suffered from heart problems and needed to be on a salt-free diet. In 1949, the sudden death of a number of such patients was found to be caused by lithium poisoning. The treatment was immediately banned and later the US FDA found that large doses of lithium chloride could adversely affect the kidneys.

In the late 1920s just before the onset of the Great Depression, a new soft drink called ‘Bib-Label Lithiated Lemon-Lime Soda’ was introduced in the American market. One of its ingredients was lithium citrate. To project it as different from the hundreds of other lemon-lime soft drinks already available in stores, the manufacturers advertised the supposedly refreshing health benefits of the small amount of lithium in the soda. The name of the drink was later shortened to – hold your breath – ‘7 Up’ which in the 1940s became the third best-selling soft drink in the world! The good news for 7 Up fans is that the lithium in the soft drink recipe was discontinued after 1950.

From the 1950s, lithium began to be used as lithium deuteride, serving as a solid fusion fuel in thermonuclear weapons, including the hydrogen bomb. Consequently, the demand for lithium rose considerably during the Cold War because of the production of nuclear fusion weapons. But, its demand decreased by the end of the nuclear arms race, resulting in a decline in prices of the metal.

Once commercial production of lithium commenced, till around the mid-1990s, the two main applications of the metal included its use for decreasing the melting temperature of the glass and for enhancing the melting behaviour of aluminium oxide during the Hall-Héroult process for manufacturing aluminium.

Lithium and its compounds have a host of other industrial applications as well. A magnesium-lithium alloy is used for armour plating. Aluminium-lithium alloys are used for weight reduction in aircraft, bicycle frames, and high-speed trains. Its low thermal expansion coefficient makes lithium suitable for producing glass that is resistant to sudden heating or cooling. It is therefore used for making heat-resistant crockery and other special ceramics and glasses, including the Mount Palomar telescope’s 200-inch mirror. Lithium stearate is added to petroleum to make a thick high-temperature lubricating grease that is used in the military and has industrial, automotive, marine, and aircraft applications. Lithium chloride, one of the most hygroscopic materials known, is used in air conditioning.

In 1949, an Australian doctor John Cade accidentally found that lithium carbonate could be used to treat manic depression or what is now called bipolar disorder, reinforcing what Soranus had noticed over two millennia ago. Today, lithium carbonate pills are the medication of choice for stabilising mood swings in people with this disorder.

Lithium-ion Batteries

However, the single most important use of lithium in the modern world is in rechargeable lithium-ion batteries. With consumers demanding longer-lasting, lighter, smaller, more powerful batteries for personal devices and industrial equipment, lithium was found to be the ideal element that could satisfy all these multiple needs. Today, lithium is used for making rechargeable batteries for mobile phones, digital cameras, iPods, laptops, mp3 players, power tools, grid-scale energy storage, and electric vehicles, and also non-rechargeable batteries for heart pacemakers, clocks, and toys.

Currently, Li-ion batteries have a crucial importance because of their attractive combination of high energy and power density, and also because they help to significantly reduce greenhouse gas emissions. To avoid a possible looming shortage in future, some researchers are working on developing better ways of recycling used lithium-ion batteries for recovering lithium. Others are focusing on improving the energy density and safety of the batteries.

References

  1. John Emsley: Nature’s Building Blocks: An A-Z Guide to the Elements – Oxford University Press, 2011
  2. William Thomas Brande: A manual of chemistry – New York, Pub. by George Long, 1821, pp 190
  3. Royal Society of Chemistry: Periodic Table – Lithium – http://www.rsc.org/periodic-table/element/3/lithium
  4. Lee R. McDowell: Mineral Nutrition History: The Early Years – First Edition Design Publishing, July 2017, pp 582-583
  5. Elizabeth Miller: 10 Facts About Lithium – Mental Floss, 3 April 2018
  6. Nathan Hurst: Charging ahead: The future of batteries – Smithsonian.com, 7 March 2017, https://www.smithsonianmag.com/innovation/charging-ahead-future-of-batteries-180962414/
  7. Andrew Tarantola: Where the Most Important Part of Your Battery Comes From – Gizmodo, 2 July 2013, https://gizmodo.com/where-the-most-important-part-of-your-battery-comes-fro-586442784
  8. Los Alamos National Laboratory: Periodic Table of Elements – Lithium – http://periodic.lanl.gov/3.shtml.

Filling of powders into bags – Challenges and Solutions.

Chemical Industry Digest
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Filling of powdery bulk materials into bags is often a technical challenge. The reason is the capability of the materials to capture air between the solid particles.

Reduction of the air into the material before filling the material into bags is one important measurement to reduce the amount of air in the filled bags. Due to technical and cost aspects, a total reduction of the air is often not feasible.

Thus a further reduction of the air during the bag filling process is desired. Bags with a certain de-aeration capacity allow de-aeration during and after filling.

Product properties: Good to know about them!

During the production of powders, the solid particles are often aerated with air. Due to the very small particle size and the particle shape of the powder, the air escapes very slowly.

If the bag filling is done directly after blending, most of the air which was added to the Powder during this process will be filled into the bags together with the Powder.

Figure 1. Decreasing of the filling level the bag due to de-aeration.

Since the air decreases the bulk density, relatively large bags have to be used to fill the powders in.  Because de-aeration is a function of time the air will escape after filling of the bags. Due to the de-aeration, the filling level in the bags will decrease (Figure 1) and the filled bags are fluffy, whereas compact bags are easier to handle and save logistic costs.

Consequently, the de-aeration of the powders before feeding into the bag filling systems is of huge interest to the powder production industry and its customers. The installation of pre-hoppers is a promising approach to answer to this interest.

Figure 2 Installation of a pre-hopper for de-aeration of powders before filling in bags

Figure 2 shows a common arrangement of bag filling machines in the industry (A).  The bag filling machine is installed directly downstream of a blender or huge silo. With this arrangement, all air which was added to the product, for blending or another process will be filled together with the product into the bags.

By installation of pre-hoppers (B) for de-aeration of powders a certain percentage of the air can escape from the product before filling into bags.

Figure 3 Basic working principle of pre-hoppers for de-aeration.

The basic working principle of pre-hoppers for de-aeration (Figure 3) is as follows:

  1. Filling of pre-hopper.
  2. Filling stop, de-aeration of material during a certain resting time and discharging into bag filling machine.
  3. Filling start and continuing of discharging into bag filling machine.

The filling level in the pre-hopper is controlled by level switch signals to start and stop feeding and discharging of the pre-hopper.

Bag Properties: How to utilize them!

Whereas a de-dusting filter is working due to under-pressure (with reference to atmospheric pressure) inside the system, an effective valve bag filling system for filling of powders is working due to overpressure inside the bags.

Figure 4 The inverted filter principle of valve bags.

Porous or perforated bag materials allow air to escape from a bag inside to outside due to the pressure difference between bag inside and outside, whereas the solid particles can’t pass the thin drains (Figure 4).

To maintain an overpressure inside the valve bags the connection of the bags to the filling systems has to be pressure-tight. The design of the relatively small valves of the bags allows the usage of filling spouts with inflatable sleeves at the filling systems. The filling systems have to be designed to create overpressure in the bags.

Figure 5 De-aeration during filling bags.

Figure 5 illustrates the main advantage of a porous or perforated valve bag compared with an open mouth bag.

  1. A high percentage of the air – captured in the bulk material – can escape during the filling process due to the overpressure in the bag.
  2. A further percentage of air will escape during a short filling brake after filling of 90 % of the target weight.
  3. Only a small certain percentage of air will remain in the bag after finishing the filling process. The amount of air depends on the properties of the bulk material and the properties of the bag.

Valve bag filling machines: What to know about them!

The HAVER M Series Filling Machines with Horizontal Impeller Filling System are designed to fill powdery bulk materials into valve bags, whereat the filling system is creating an overpressure inside the bags during filling.

The overpressure and the using of porous or perforated bag materials result in a filter effect, which allows air to escape from the bags, whereas the solid particles remain in the bags.

The design of the HAVER M Series Filling Machines considers modularity and scalability, in order to provide the most productive and economical solutions for different requirements. In case requirements change after a certain operation time filling capacities can be increased by installing additional machines. Manual operated systems could be automated by installing automatic bag placers. Ultrasonic Sealing systems could be installed later for automatic sealing of the bags.

Figure 6 Basic design.

According to Figure 6, the entire valve bag filling systems consists of:

  • Pre-hopper, to ensure first de-aeration of the bulk material before feeding into the filling machine.
  • Impeller system, to feed bulk material into the valve bags.
  • Impeller drive, variable speed as an option for filling of different kind of bulk materials.
  • Scissor valve, for dosing of the bulk material into the valve bags. Valve bags are weighed during filling.
  • Filling spout, to connect the valves of the valve bags with the filling system.
  • De-dusting system, to minimize dust emission.
Figure 7 The impeller system.

The impeller system (Figure 7) is the heart of the filling system. It feeds the product into the valve bag by creating an overpressure.

The modular design of the impeller system allows choosing

  • the impeller system material,
  • the impeller diameter,
  • the impeller bleeds number and design,
  • the impeller speed and
  • the filling channel diameter according to bulk materials and valve bags properties.
Figure 8 The scissor valve.

Under the most extreme conditions, independent of the bulk material type, the scissor gate is proven for dosing and complete closing of the filling channel.

The scissor gate guarantees an exact dosing of the filling flow rate during fine flow, which results in best weighing accuracy.

Three positions of the scissor gate are controlled by the HAVER MEC control system via a three-position pneumatic cylinder:

  1. Course flow, 100 % open.
  2. Fine flow, the opening can be adjusted manually according to the bulk material properties.
  3. Closed
Figure 9 The filling spout.

The filling spout (Figure 9) is the interface between the valve bag filling system and the valve bags.

Various designs are available to be chosen according to the bulk materials properties and the valve bags properties and dimensions.

Filling spouts with inflatable sleeves guarantee a material tight and overpressure tight connection of the valve bags with the filling system, which results in a dust emission free filling and compact bags.

Figure 10 The Dosing, Weighing and Filling Process.

To ensure the most efficient and economical filling process (Figure 10) the process parameters have to be adapted to the bulk material properties (e.g contained air) and valve bag properties (e.g. de-aeration capacity).

  1. High material flow and no filling interruption, for materials with less contained air and bags with high de-aeration capacity.
  2. Low material flow and two filling interruptions, for materials with much-contained air and bags with low de-aeration capacity.
Figure 11 The HAVER MEC Control System.

The dosing and weighing of the bulk material are controlled by the HAVER MEC Control System (Figure 11). The HAVER MEC Control Systems allows to program and to save 99 different sorts to fill a different kind of bulk materials with different filling weights into different bags.

Each sort comprises a set of parameter to adjust:

  • filling weight
  • material flow (kg/s) by impeller speed and sequence
  • course and the fine flow amount
  • sequence and duration of fluidization

Registered Office & Work

HAVER IBAU INDIA Pvt. Ltd.

Phone :    +91 2676 306-600
Survey No. 32/4/41 & 42, Khandiwada, Baroda-Halol Road, Post Asoj Vadodara – 391 510, Gujarat.
Fax:         +91 2676 306-999
E-mail:     info@haveribauindia.com
Website:  www.haveribauindia.com

Courtesy: Guido Neu (Technical Expert)

Chemingineering | War of Nerves

K. Sahasranaman (Independent Industry Consultant)
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Chemingineering | War of Nerves

The month of April is important in the history of Chemical Weapons. This month, our columnist examines the close links between chemical weapons and pesticides. Some of the precursors of chemical warfare agents have benevolent commercial applications and are required for synthesis of useful products in plastics and pharmaceuticals. The threat of chemical weapons will persist as long as chemical pesticides continue to be manufactured.

On April 29 each year, since 2005, an Annual Day of Remembrance is observed in memory of all victims of chemical warfare. It was on this day in 1997 that the Chemical Weapons Convention (CWC) entered into force. April is significant for yet another reason in the history of chemical weapons. It was on April 22, 1915, that German army unleashed chemical warfare. In the first recorded use of chemical weapons, 6000 canisters containing 168 tonnes of chlorine were released into the trenches occupied by French and Algerian soldiers near the Belgian city of Ypres. 5000 soldiers died within minutes. This was in total disregard of The Hague conventions of 1899 and 1907, which prohibited the use of poisonous gas in warfare. What an irony for a chemical that has saved more lives in the last 100 years than any other in human history!

Proliferation

One million casualties and 90,000 deaths were reported in WW-I due to use of chemical weapons from both sides. Phosgene and mustard gas were used with impunity. After the war, western countries signed the 1925 Geneva Protocol, that banned the use of chemical and biological weapons. But that did not deter them from inventing new increasingly toxic chemicals. Germany developed nerve agents like Sarin, Tabun and Soman. Britain responded with VX. USA never signed Geneva Protocol. Between 1961 and 1969 US military spent $2 billion in stockpiling chemical weapons. Hundreds of thousands of tonnes of obsolete chemical weapons were directly dumped into the sea during this period. But for the Dugway accident of March 1968, the clandestine testing of chemical weapons by the US military would not have been brought to light. An accidental release of the nerve gas VX at higher than intended height led to the death of 6000 sheep and triggered a nationwide debate on chemical weapons.

The recent incidents in Syria have brought chemical weapons to the forefront again. And the chemicals used are getting more potent. Novichok, the nerve agent allegedly used on a Russian spy in England recently, is reported to be 8 times more powerful than VX.

Dual Use

Some of the weapon grade chemicals and their precursors have perfectly legitimate and benevolent applications in many areas. These include not just insecticides and herbicides but also plastics, pharmaceuticals and cosmetics. Phosgene, one of the deadliest chemical weapons of yesteryear, is a classic example. It is a valuable building block for synthesis of many useful products. Millions of tonnes of phosgene are used for the manufacture of toluene di isocynate (TDI), an intermediate of polyurethanes. Phosgene is also used in large quantities in the manufacture of polycarbonates. It is this dual use that makes the chemical industry jittery. The battle against chemical weapons has to be fought with a double-edged sword.

To address this knotty issue, CWC has adopted a very broad-based definition of chemical weapons. The term chemical weapon is applied to any toxic chemical or its precursor that can cause death, injury, temporary incapacitation or sensory irritation through its chemical action. Munitions or other delivery devices designed to deliver chemical weapons, whether filled or unfilled, are also considered weapons themselves. CWC classifies the chemicals and their precursors that could be used as chemical weapons into three schedules. Schedule-1 chemicals have the highest risk and are rarely used for peaceful purposes. Schedule-2 chemicals are mostly precursors to the manufacture of Schedule-1 chemicals and are not produced in large quantities for commercial applications. Schedule-3 chemicals are produced in large quantities for purposes not prohibited by the convention. Phosgene falls under Schedule-3, which also includes apparently innocuous precursors like thionyl chloride and triethanolamine.

Many of the weapon grade chemicals and their precursors are used in the pesticide industry. Sarin, a chemical weapon now, was once used as an insecticide. Pesticides and insecticides are a big bugbear for the chemical industry in its fight to regulate and monitor chemical weapons. Nerve agents were accidentally invented while seeking a more effective pesticide. They have similar molecular structure and the way a nerve agent acts on a human being is exactly the way a pesticide kills an insect.

Drones

Delivery and detection of chemical weapons have both gone hi-tech. Terrorists have reportedly used drones for dispersal of chemical warfare agents. Drones are also now being deployed to detect chemical weapons. Drones fitted with ion-mobility spectrophotometer can detect 20 different chemical warfare agents in parts per billion concentrations. The drones are also equipped with sample collectors to store substances for future forensic analysis. Thus, even drones have a “dual use”.

Disposal

CWC requires the signatory countries to declare their existing stockpiles of chemical weapons and destroy them under strict international monitoring. Further it requires them to dismantle the chemical weapons production facilities or convert those facilities to peaceful purposes. USA and Russia, the two largest owners of chemical arsenals have missed multiple deadlines in fulfilling their obligations under CWC. While Russia finally eliminated its stockpile in September last year, USA targets to do so only by 2023.

Safe disposal of unused chemical weapons is a looming problem. Chemical weapons are destroyed by incineration. US army has built a highly automated incineration plant at the cost of USD 4.5 billion for destroying its huge stockpile of obsolete chemical weapons. But the plant has reportedly run into snags with robots unable to open the shells containing the mustard gas due to higher than expected corrosion. Manual intervention by workers donning protective equipment would be necessary. US army is now considering an alternative method of disposal by detonating the shells in closed chambers at temperatures of 540 degrees C. But the local community is apprehensive of contaminants being released into the air.

Research is on for developing new methods of detecting and disposing toxic chemicals. UK based research team has found that mustard plants soak up toxic chemicals from the soil just the same way they would absorb nutrients. This not only provides for improved detection of trace contaminants present in the soil, but also their safe disposal. Having drawn the chemical agents out of the soil, the plants could be incinerated under safe conditions.

Epilogue

The juxtaposition of “chemical” and “weapon” is uncomfortable for the chemical industry, which is already facing the brunt of poor public image. While non-phosgene route has been successfully commercialised for polycarbonate manufacture, it has not met with similar success in case of TDI. It is estimated that without chemical pesticides, the world could lose one-third of its farm output each year. And that is something we just cannot afford. As long as chemical pesticides are manufactured, the threat of chemical weapons will remain.

Readers’ responses may be sent to k.sahasranaman@gmail.com or       chemindigest@gmail.com

Hans Fischer (1881 – 1945)

Veena Patwardhan
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Hans Fischer (1881 – 1945)

On November 13, 1930, the announcement for two of that year’s Nobel Prizes was made. The first was the Nobel Prize in Physics awarded to 42-year old Indian physicist Sir Chandrasekhara Venkata Raman, Professor of Physics at Calcutta University, for his work on the scattering of light and the discovery of the Raman effect named after him. The second was the Nobel Prize in Chemistry awarded to 49-year old German chemist Hans Fischer, Professor of Organic Chemistry at the Technical University of Munich, for his research towards discovering the molecular structure of the biological pigment hemin (one of the two components of haemoglobin – the non-protein, iron-containing one) and chlorophyll, and especially for his synthesis of hemin.

One of Germany’s greatest organic chemists, Hans Fischer’s crowning achievement was being honoured as a Nobel Laureate, a fitting reward for the years he devoted to carrying out intensive research on natural pigments and on the chemistry of pyrroles. His work made it possible to synthesise hemin (or haemen) from simpler organic compounds. Fischer’s breakthrough feat was producing a synthetic hemin that was indistinguishable from the natural hemin obtained from haemoglobin.

From Classical Studies to excelling in Organic Chemistry

Hans Fischer was born on 27 July, 1881 in Hoechst on the River Main, a major centre of chemical industries in Germany. His father, Dr. Eugen Fischer, being the Director of a chemicals manufacturing company, he was exposed to the field of chemistry from a very young age. He began his schooling at a primary school in Stuttgart and then completed his matriculation in Wiesbaden at the Humanistische Gymnasium, a reputed humanities-oriented grammar school where children learnt about the Classical Age and the cultural history of the ancient Greeks and Romans.

In 1899, he joined the University of Lausanne, simultaneously commencing studies in chemistry and medicine. He completed his doctorate in chemistry from the University of Marburg in 1904 and got his Doctor of Medicine degree in Munich in 1908, studying under Friedrich von Muller, the renowned physician and clinician. For the next two years, he worked in Berlin as an assistant to the eminent chemist Emil Fischer at the First Berlin Chemical Institute. Emil Fischer had won the Nobel Prize in Chemistry in 1902 for his extraordinary work on sugar and purine syntheses. Under his direction, Hans Fischer studied peptides and sugars.

But it was F. von Muller, his former professor and supervisor, who sparked Fischer’s interest in pyrrole pigments by inviting him to work with him at the well-known Second Medical Clinic in Munich in 1910. Under Muller, he began to examine the composition of the bile pigment bilirubin, something he would continue to be engaged in during the decades that followed. He spent a year or so there studying the relationship and similarities between the pigments of blood and bile alongside Muller and other researchers, before working as a lecturer for four years in the same city.

After that, in 1916, he moved to neighbouring Austria on being invited to succeed Adolf Windaus (who would go on to win the Nobel Prize in Chemistry in 1928) as the Professor of Medical Chemistry at the University of Innsbruck. Delighted by the tranquil beauty of the surrounding Alpine countryside, Fischer enjoyed skiing and mountain climbing here in his free time. He spent two happy years in Innsbruck till tragedy struck unexpectedly while he was out mountain climbing with his father in the Alps. Right before his very eyes, his father died tragically on falling into a deep crevice.

For the next three years, Fischer then held the chair of Medical Chemistry at the University of Vienna before being appointed as Professor of Organic Chemistry at the Technische Hochschule (Technical University) in Munich in 1921, a position he held till his death. In the beginning, many questioned the wisdom of appointing a professor of medicine to a position of responsibility at a technical institute.

But Fischer proved all the people who doubted his capabilities wrong. He successfully set up a big and extremely productive research laboratory well equipped for systematic investigations of all facets of the chemistry of pyrrole, bile pigments, and other related compounds. He also soon became hugely popular with his students and his staff as well. His enthusiasm and commitment to his work inspired a large number of graduate students to work with him as his loyal disciples. They were equally committed to the research projects he had undertaken and were determined to help him accomplish his goals. Fischer trained several students to become brilliant chemists and was instrumental in many of them emerging as industry leaders and distinguished academics in Germany and abroad. And not only was Fischer a great teacher and researcher, he was also an excellent administrator.

Indefatigable researcher, ground-breaking discoveries

Fischer devoted around three decades of his life to the study of the highly significant biological compounds haemoglobin, chlorophyll, bilirubin, and other bile pigments. In 1921, he began his research work on hemin. At that time, not much work had been done on the synthesis of pyrroles – the molecules that impart colour to different biological substances. The work was time-consuming and laborious and with the help of his large team of microanalysts and doctoral students, he carried out over 60,000 microanalyses in his lab. Finally, he discovered the molecular structure of hemin and showed that it comprised four pyrrole rings linked by bridges, with an atom of iron in the centre. In 1929, he successfully synthesised hemin.

Fischer then began investigating the structure of the chlorophyll molecule and the pyrroles he obtained from the decomposition of chlorophyll. Having only partly succeeded in the difficult task of synthesising chlorophyll, he turned his attention to the bile pigment bilirubin that he had first become acquainted with in Muller’s lab. Till then, though bile pigments had been discovered several decades earlier, hardly anything was known about their chemical composition. After almost a decade of studying the bile pigments, Fischer finally discovered the molecular structures of both, bilirubin, that gives rise to the yellow colour in jaundice sufferers, and biliverdin, that gives a yellowish colour to bruised skin. In 1942, he synthesised biliverdin, and in 1944, he succeeded in the more complex activity of synthesising bilirubin, thus completing the work Muller had begun.

Fischer authored over 300 research papers, most of which were published in the scientific journals Liebigs Annalen der Chemie and Hoppe-Seylers Zeitschrift für physiologische Chemie. His work paved the way for further research on natural pigments. With two of his colleagues, he also co-authored three volumes of a major work on pyrrole chemistry – Die Chemie des Pyrrols (The Chemistry of Pyrroles).

Acknowledgments

In recognition of his extensive scientific work in the field of natural pyrrole pigments, the title of Privy Councillor (Geheimrat Regierungsrat) was conferred on Fischer in 1925. He was awarded the Liebig Memorial Medal in 1929, the Nobel Prize in 1930, and the Davy Medal in 1937. In 1936, Harvard University honoured him by conferring an honorary doctorate on him. The lunar crater Fischer is named after both Hans Fischer and Emil Fischer. The Technical University of Munich holds the Hans-Fischer Symposium in his honour in November each year in the Hans-Fischer Lecture Hall of the Chemistry Department.

Completely dedicated to his work, Hans Fischer married rather late in life, when in his fifties. He and his wife Wiltrud didn’t have any children. He however continued to be an avid lover of mountain climbing and skiing. Suffering from serious ‘surgical tuberculosis’ when he was younger didn’t deter him from fearlessly engaging in strenuous outdoor activities. Sadly, he was so devasted when the renowned laboratory he had set up and almost all his life’s work was destroyed during the bombing of Munich towards the close of World War II that he took his own life by committing suicide at the age of 63 on Easter Sunday, 31 March, 1945.

Incidentally, Emil Fischer, the celebrated Nobel Laureate he had briefly trained under, was also believed to have ended his own life. He had suffered from spells of depression due to personal tragedies – his wife died just seven years after they got married, and two of his three sons died in their twenties during World War I. He is thought to have killed himself in 1919, finally overcome by depression after being diagnosed with terminal intestinal cancer.

Notwithstanding their tragic ends, both Emil Fischer and Hans Fischer have left behind a glorious legacy and are shining luminaries in the long line-up of outstanding German chemists.

References

  1. NobelPrize.org: Hans Fischer – Biographical – Nobel Media AB 2014, https://www.nobelprize.org/nobel_prizes/chemistry/laureates/1930/fischer-bio.html
  2. YourDictionary: Hans Fischer – http://biography.yourdictionary.com/hans-fischer
  3. Soylent Communications: Hans Fischer – http://www.nndb.com/people/376/000100076/
  4. Adolf J. Stern: Hans Fischer (1881–1945) – Annals of the New York Academy of Sciences, 206: 752-761, October 1973, https://nyaspubs.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1749-6632.1973.tb43252.x
  5. Encyclopaedia Britannica: Hans Fischer German Biochemist – https://www.britannica.com/biography/Hans-Fischer
  6. Encyclopaedia of world biography: Hans Fischer – https://www.encyclopedia.com/people/history/historians-miscellaneous-biographies/hans-fischer
  7. Zexia Barnes: 1930 Nobel Laureate Hans Fischer – Nobel Laureates in Chemistry, 1901-1992, James K. Laylin, Editor, Chemical Heritage Foundation, 1993.

Mercury – Shiny liquid metal with a dark side

Veena Patwardhan
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Mercury – Shiny liquid metal with a dark side

Mercury, the only metal that is a liquid at room temperature, has fascinated people right from ancient civilisations and alchemists to the scientists of modern times.

One of the transition elements of the periodic table, the silvery metal, also called quicksilver in English, was originally called hydrargyrum, a Latinised form of a Greek word meaning ‘water-silver’. It’s chemical symbol Hg has been derived from this name. With atomic number 80, mercury is a very heavy metal. A one-pint beer mug of it would weigh around 8 kilos. Imagine the strain of lifting that with one hand!

Mercury is also a rare metal, occurring in the earth’s crust at an average concentration of around 0.08 g per ton of rock. It is found in the elemental form in very small quantities. Its most abundant ore, the red mercuric sulphide – cinnabar – has been used for extracting mercury and for various other purposes across the world for millennia. From ancient times, people have been condensing the vapours emitted on heating cinnabar to obtain pure mercury.

The ‘First Matter’

Mercury was given its present name by 6th century alchemists. Like Islamic alchemists, European alchemists too believed mercury was the ‘First Matter’ and that it was present in all other metals. Mercury was fundamental to the art of alchemy which itself led to the establishment of the philosophical tradition on which the principles of the scientific method are based.

Alchemists believed that mercury when combined with other base metals in the right proportions could be transmuted into gold. We now know that is not true. But, perhaps the basis of what the alchemists believed was mercury’s ability to combine with a noble metal like gold, something that was known even to ancient civilisations. Down the ages, man has exploited mercury’s remarkable property of dissolving gold and silver and forming amalgams with them to extract these precious metals from alluvial river sediments and mines. (They separated the dissolved gold or silver from the amalgams that were formed by distilling off the mercury.) For instance, the Spanish conquerors used mercury obtained from the huge cinnabar deposits in the mines of Huancavelica, Peru, for extracting silver from silver mines in South America. Similarly, during the well-known California gold rush of the 19th century, miners used mercury obtained from cinnabar to extract gold from river sediments.

Other historic and traditional uses

The Chinese used cinnabar, the naturally occurring mineral of mercury, in different medicines, and as a pigment for imparting a bright red colour to lacquer and ceramics. Referred to in ancient Indian literature as rasasindur, cinnabar was used in ayurvedic medicines.

The Romans used it as a pigment in paintings and in rouge-like cosmetics for colouring cheeks. The ancient Greeks were known to use it in ointments for healing wounds. Its use can even be seen in Neolithic-Age (around 10,000 to 3000 BC) cave paintings. During the Middle Ages, cinnabar was mixed with the wax used for seals stamped on formal and official documents.

Large quantities of liquid mercury have been discovered in Egyptian tombs. In Islamic Spain (8th-15th century AD), sizable reflecting pools filled with mercury served as mirrors in which Caliphs could gaze at their reflections. Many castles of that period were even known to have mercury fountains.

Liquid mercury’s unique property of not wetting or sticking to glass, together with its rapid and uniform volume expansion, made it ideal for thermometers, thus resulting in it playing a crucial role in the Scientific Revolution that got underway in Europe around the 16th century. Today, we have digital thermometers, but they are not as accurate as the mercury ones that are still used in many homes. Barometers and manometers exploit two of mercury’s other properties – its high density and low vapour pressure.

Many may remember the old antiseptic of choice used in homes for curing cuts and bruises – mercurochrome – a tincture that stained the skin red and contained a small quantity of a mercury compound. Also, dental amalgam fillings containing around 50% of elemental mercury by weight are in use since around 150 years. Some modern day uses include electrical switches, high-pressure mercury-vapour lamps, compact fluorescent lights, industrial fungicides, and electrolytic cells and catalysts for chemical manufacturing.

Unfortunately, this useful and amazingly lustrous metal also has a dark and dangerous side.

A two-faced metal

Notwithstanding the fact that the use of mercury and its compounds has been closely linked to human history for long, the fact is that mercury is highly toxic. In fact, it is the most poisonous non-radioactive element on earth. Like lead, mercury is a deadly neuro-toxin. It affects the cerebellum, the part of the brain that co-ordinates our movements and the neurological damage it causes is irreversible. Besides, it damages the kidneys and other vital organs too.

The major mercury compounds include: mercurous chloride or calomel – prescribed till recently as a laxative and diuretic and as a cure for syphilis, and added to teething powders for babies, the mercury poisoning in these tiny tots showing up as the ‘pink disease’ that caused an unnaturally bright pink colouration of their fingers, toes, nose, cheeks, and buttocks; mercuric chloride or corrosive sublimate – a poisonous chemical used as a disinfectant; and mercuric sulphide or vermillion (present in the ore cinnabar) – a less poisonous compound mainly used as a paint pigment.

In the 19th century, hatters in the hat industry ended up suffering from ‘hatter’s shakes’ and ‘mercury madness’ due to their handling of another mercury compound – mercuric nitrate – for soaking the pelts of rabbits and beavers and turning them into felt for making hats. The peculiar condition that afflicted these industrial workers gave rise to the phrase ‘mad as a hatter’, as also the name of the well-known character in Lewis Carroll’s Alice in Wonderland – the Hatter, popularly called the Mad Hatter, being referred to in the book as mad.

Mercury poisoning though rare today, claimed many more lives in the past, even the Romans and Greeks being aware of its toxicity. From around the 16th to 19th centuries when metallic mercury and calomel were used for treating syphilis, a large number of people died of slow mercury poisoning.

Till a few decades ago, teachers too were known to encourage their students to check out the cold, clammy liquid mercury in school labs. Alarming though that may seem, the reassuring fact however is that more than metallic mercury that is poorly absorbed through touch, it is the vapours emitted by it that are extremely poisonous.

Around half the quantity of mercury vapours entering our environment comes from volcanic eruptions and other geological occurrences – processes over which we have no control. But the other half is a result of human activities.

Of this, the mercury vapour arising from accidentally smashed fluorescent bulbs, broken thermometers, or improperly discarded dental fillings account for a tiny fraction of the 2000 or so tonnes of mercury released by humans into the atmosphere each year. Around a quarter of the atmospheric mercury comes from power generation when coal, a fuel that contains traces of mercury, is burnt. Gold mining is another cause of mercury emissions.

Also, while almost all compounds of mercury are toxic, the most lethal of them all is methyl mercury, an organic form of the metal that harms the central nervous system, even causing foetal deformities. It is a deadly pollutant in rivers and lakes. When mercury-containing industrial wastes are dumped into water bodies, anaerobic microbes convert inorganic mercury into methyl mercury that ultimately makes its way into the bodies of fish. People who eat such contaminated sea food become victims of mercury poisoning.

Introduction of safety regulations

Thankfully, in the last few decades, a number of safety regulations and modifications in industrial processes related to mercury have been introduced. The emphasis is now on safer processes for extracting mercury. The newer methods involve dissolving cinnabar in solutions of sodium hypochlorite or sulphide, and then recovering mercury by precipitation with zinc or aluminium or through electrolysis. Also, plants that use cinnabar for manufacturing sodium hydroxide and chlorine by electrolysis of brine are expected to be phased out by 2020. Similarly, other uses of mercury that are being gradually phased out or are on their way out include its use in felt production, and in the manufacture of batteries, fluorescent lights, thermometers, barometers, and medicines.

Special equipment is being installed in power stations, cinnabar smelters, gold refineries, and cement works for trapping and collecting the mercury vapours emitted. In 2013, over 90 countries signed the UN’s Minamata Treaty whose objective is to impose controls and reductions on a range of products, processes, and industries where mercury is used, released or emitted.

What can you do at the individual level? Make sure inoperative or broken domestic products containing mercury are disposed of safely, remembering to use some common-sense measures as well. For example, ensuring you’re not wearing any gold jewellery while handling spilled mercury. That just might prove to be too costly!

References

  1. WebElements: Mercury: historical information – https://www.webelements.com/mercury/history.html
  2. Royal Society of Chemistry: Periodic Table: Mercury – http://www.rsc.org/periodic-table/element/80/mercury
  3. Anne Marie Helmenstine, Ph.D.: 10 Mercury Facts (Element) – ThoughtCo., 3 April, 2018, https://www.thoughtco.com/mercury-element-facts-608433
  4. K. Kris Hirst: Cinnabar – The Ancient Pigment of Mercury – ThoughtCo., 8 February, 2017, https://www.thoughtco.com/cinnabar-the-ancient-pigment-of-mercury-170556
  5. John Emsley: Mercury – Nature’s Building Blocks: An A-Z Guide to the Elements, Oxford University Press, 2001
  6. Dr. Doug Stewart: Mercury Elements Facts – https://www.chemicool.com/elements/mercury.html
  7. Joel D. Blum: Mesmerized by mercury – Nature Chemistry, 21 November, 2013 online, https://www.nature.com/articles/nchem.1803
  8. Justin Rowlatt: Mercury: A beautiful but poisonous metal – BBC News Magazine, 30 November, 2013, http://www.bbc.com/news/magazine-25130770
  9. Julie Sloane: Mercury: Element of the Ancients – Dartmouth Toxic Metals Superfund Research Program, 26 July, 2016, https://www.dartmouth.edu/~toxmetal/mercury/history.html.

Chemical Industry Digest- Apr 2018

Chemical Industry Digest
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Chemical Industry Digest- Apr 2018

Articles covered in this issue:

Real Time Monitoring Spurs Energy Savings
Philippe Baudet, PRoSim; France Fabien Joly, Total’s Normandy Refinery, France.
In this article, the author describes how a refinery gains energy efficiency benefits by using utilities optimization software.

Noise Reduction in Control Valve
V. Murugappan, Sethumadhavan Vittal, Fluor Daniel
This article determines the different methods that can be used to limit the noise generated by control valves for ensuing safety of the plant and its workers.

Electrical Equipment & System Maintenance in Corrosive and Dusty Environs
Raghava Chari – Independent Consultant
This article discusses how frequently flashing electrical equipment and systems’ posed safety hazards, back-breaking restoration tasks and lost production in a vintage pioneering single stream centrifugal compressor technology based NH3, urea, and NPK plants located in South India. The author’s solutions are also provided.

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Why no concern about the liquidation of petroleum refinery project in Cuddalore?

Chemical Industry Digest
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Why no concern about the liquidation of petroleum refinery project in Cuddalore?

It is surprising that neither the Government of Tamilnadu nor the political parties or fringe groups in Tamilnadu have expressed concern that a six million tonne per year capacity petroleum refinery project in Cuddalore with an estimated investment of more than Rupees 15000 crore is likely to be liquidated soon.

This Nagarjuna Oil Refinery project at Cuddalore is a joint venture of the private promoter and Tamil Nadu government-owned  Tamil Nadu Industrial Development Corporation and the project implementation started in 2008.As per the original schedule, the project should have been completed by 2012.During the last Global investor’s meet in Tamil Nadu, the then Chief Minister Ms. Jayalalitha declared this project  as the anchor client for the Petroleum, Chemicals  and Petrochemicals Investment Region ( PC & PIR), where several thousand crores of rupees of investment by way of additional projects were declared as possible and as the   objective.

This Nagarjuna Oil Refinery project is proposed to be implemented to produce several basic petrochemicals such as naphtha, LPG etc.,  which can provide the feedstock for many derivative chemicals and downstream industries with high demand potential, The project holds the prospects of accelerating the industrial growth in Tamil Nadu substantially and generating large employment. The project is spread around 2000 acres with several infrastructure facilities.  By 2011, around 58% of the construction of the project was already completed.

Unfortunately, the project came to a standstill due to the fund constraints and the inability of the project promoters that include the original promoters  Nagarjuna Fertilisers and Tamilnadu Industrial Development Corporation, to raise the required funds for completing the project implementation.

As the project virtually got stranded, the company has now entered into liquidation process under the Insolvency and Bankruptcy code (IBC), after the 270-day deadline offered by National Company Law Tribunal  Chennai Bench to identify a suitable bidder to take over the company.

It is not as if there were no bidders to take over the project. Four bidders including the public sector BPCL   showed interest. Considering the fact that the company had a debt of over Rs. 8000 crore and further investments were required and considering the long-term economic prospects for the project,  the bidders submitted the bid amount.  The bid submitted by the bidders were lower than  Rs. 1450 crore, set as liquidation valuation by the Resolution  Professional. Therefore,  all the bids were rejected by the Resolution Professional.

The Resolution Professional has shown lack of foresightedness and poor understanding of the implications of liquidating such an important project, which is around 58% already complete.

The decision to go for the liquidation of this large petroleum refinery would virtually mean that the project would be sold at auction and perhaps, the equipment would be bought for scrap value.

When there were four bidders to take over the project,  would it not be advisable to choose one among the four bidders to take over the project after considering the merit of the individual proposal in a holistic way? Who is going to gain by simply liquidating the project that has enormous potentials?The haircut that the bankers and financial institutions will have to put up with would be much more by liquidating the project.

It is surprising that the Resolution Professional has not cared to examine the feasibility of safeguarding the project by splitting the project into three or four entities, as separate profit centers, that would have attracted more bidders This option is technically and economically feasible.

One wonders why Tamil Nadu government has not expressed its concern about the move to liquidate this significant project and why it has not taken more dynamic steps to prevent the liquidation.  This makes one suspect as to whether the Tamil Nadu government to lack appreciation of the significance and need for this massive project to promote all-around industrial progress of the state.

This Nagarjuna Oil Refinery Project at Cuddalore has already received all environmental clearance and face no controversies.

Tamil Nadu politicians, who seem to be all the time looking for opportunities to conduct demonstrations and hold protest meetings and shout from the rooftop about their commitment to the progress of the state,  are exhibiting deafening silence at the loss of this great investment opportunity for the state.

One wonders whether Tamil Nadu politicians know about this project at all or they remain unconcerned about its fate.

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