Author Archives: gaussling

About gaussling

Gaussling is a senior scientist in the chemical business. He occasionally breaks glassware, spreads confusion and has been known to generate new forms of hazardous waste. Gaussling also digs aerospace, geology, and community theatre.

Taking the dragon out for a walk

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Plan on working with HF? A friend who was president of an HF manufacturing company once gave me some valuable advice. He said there are several things to do before the plastic bottle of HF arrives. First, have a well ventilated fume hood available. Next, read up on HF first aid. Try to identify a hospital ER that could cope with an HF incident. How do you do that? You call and ask questions. Get some calcium gluconate salve.  Learn what to do with it.  If you have an incident, you will need to get decontaminated before you arrive at the hospital, otherwise there may be delays in getting teatment  by the medical staff.

Here is my personal policy. You follow your own policies. If you handle HF and do not have a specific response plan, get one in place. If you handle this acid, you need to have a plan.

Do not rely on the local fire department to know what to do.  They’ll want to take charge as soon as they arrive. Time will be lost as they ignore the staff of chemical experts standing right there while they confer on a plan. I’ve seen variants of this many times. It might transpire that the firemen will be ordered to stand clear of you until their commander has a plan for dealing with the contamination. So there you’ll sit.

Your main concern in a major splash incident is to get decontaminated.  Your lab buddies who are there with you need to know how help you with this so there is no delay in getting you decontaminated. Do not wait for the fire department to come decontaminate you. Strip off contaminated clothing and get under the shower pronto, even if you have to use your one good arm to drag yourself there.

HF is a weak acid with a pKa of 3.17.  It is somewhat skin permeable and will cause deep tissue injury.  In addition to the general hydrolytic havoc associated with an acid exposure, HF delivers fluoride which scavenges calcium and will precipitate calcium fluoride in your tissues. That is what sets an HF exposure apart. This link to Honeywell Specialty Materials is especially well written and informative.

Avoid inhalation exposure and provide for splash protection.  If you are heating it, consider using a full face respirator with appropriate cartridges when opening the sash of the hood when  handling the reaction mixture.  Wear a long rubber or plastic gloves and apron and make sure that your lab coat is non-absorbant. Be fastidious.

Don’t be afraid of HF. It is a lot like a table saw. You just have to know how to behave around it. And like a table saw, it’ll take body parts or worse from the careless or the complacent. You have to handle it carefully every single time. Be in the moment. Don’t get distracted by talkative bystanders. Pay attention to what you’re doing.

Retorting the Auriferous Spud

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Gold miners of the 19th and early 20th century had a processing advantage over todays gold miners despite all of their modern diesel powered trommels, pumps, and sluices. Some early placer miners had access to mercury or quicksilver. Auriferous fines could be concentrated in a small container with water and a few ounces of mercury would be added to extract the gold as an amalgam. Or, the concentrates could be contacted with mercury-coated copper for the same effect. Mercury coated copper pans or flat plates were often used to scavenge gold and isolate it as the amalgam.

Today, the use of mercury is strictly forbidden in mining operations around the world. But there was a time when mercury was a key part of the miners toolkit.  Many extraction schemes were developed to concentrate gold into a small package.  Panning or the use of a shaker table would provide nuggets and dust as concentrate. But often there was heavy black sand comingled with the gold dust.  Isolation by amalgamation followed by distilling off the mercury (retorting) would provide moderately pure gold.

For example, a simple retort may be made from a pipe nipple with a cap on the bottom and a top connector attached to a long condenser tube that could be cooled with stream water. The retort vessel was set into a campfire and perhaps a cloth was wrapped around the condenser tube and wetted to knock down the mercury vapors so that they could be collected in a receiver.

Curiously, there is lore about the potato retort.  My source is Eldred D. Wilson, Gold Placers and Placering in Arizona, Bulletin 168 (1961), State of Arizona, Bureau of Geology and Mineral Technology, Geological Survey Branch. In the potato retort method, a potato is cut in half and one half is hollowed out enough to accomodate an ounce or so of amalgam. The auriferous spud is wired back together and placed in the ashes of the campfire for 30-60 minutes until done. The potato is then opened to reveal a gold button in the middle. Or, so the story goes.

There were variations. Analogous to the preparation of hoe cake, digging implements were put to use in retorting duty. A potato amalgam package could be placed in a frying pan or in a shovel which would then sit in the campfire.

It’s hard to say just how effective potato retorting was compared to other methods. Admittedly, I have trouble believing that the internal temperature of the potato was high enough to do the job. It’s conceivable, perhaps, that enough Hg was cooked away to leave behind a metallic mass with some gold color.  It would be interesting to try this and then get an assay.

Wilson offers this advice- don’t eat the potato.

South Pole

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A friend and colleague is currently wintering over at the Amundson-Scott station on the south pole.  She is sending us periodic email updates on life at the station.  As they come along I’ll share bits of them.  A colleague of hers posts his observations on his blog. They recently celebrated their once-per-year sunset at the equinox.

There are all sorts of station closing activities I volunteered for early on. I trained for what is called “Flight Following” to man the Comms Center in the winter whenever any flights are flying farther South than 60 degrees. South Pole’s unique position on top of the plateau makes radio reception unusually clear while closer to the coast it is often obscured. So our job is to relay messages if we hear the pilot unable to reach his coast air traffic control. I also periodically do checks in the Power Plant so those people can occasionally get a day off.

It’s almost like a commune down here. Or at least what I assume communal living would have been like in the ’60s, Kind of a fun existence for a few months. But it is damn COLD! I took my glove off to operate my camera to film sunset up on the roof of the station – our daily temps are about -80 F, with windchill well below -100 F. A gust of wind kicked up after I had been filming for less than 2 minutes and I almost couldn’t make my hand work well enough to climb back down the steps. Today there is still a blister on my pinkie finger from frostnip. Human flesh freezes within a minute when exposed to that sort of cold. –South Pole Susan

I guess I won’t be complaining about the cold anymore.

XRF Magic

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We’ve been looking at hand held XRF spectrometers.  If you have not been introduced to this, you may be in for a real treat. A variety of companies make them- Bruker, Thermo, and Innov-X to name a few. These things are in the low-end Lexus price category, but are they ever amazing.  It’s straight out of Star Trek.

Clarke’s Third Law states that any sufficiently advanced technology is indistinguishable with magic. I gotta tell ya that these hand held XRF’s are just amazing.  You point at a sample and it gives a tally of the elements present, or most of them at least.  Some even have a built-in GPS you can punch to take a waypoint of the location of the sample you just analyzed out in the field.  It is a great tool for mineral prospecting.  

What is embarrassing is that this is the first I’ve heard of it. Our geologist friends have been using these things for a while now. 

The whole thing depends on a miniature X-ray source.  I’ve been looking into this.  For the curious folks out there, lithium niobate- LiNbO3- is a very interesting material.  Crystals of LiNbO3 have the property of pyroelectric potential. A pyroelectric crystal is one that is able to generate a polarization across the crystal faces in proportion to the temperature.  A pyroelectric xtal placed on a heating/cooling block in a vacuum is able to generate a stream of electrons energetic enough that, when stopped by a copper electrode, will generate x-rays. 

One manufacturer, AmpTek, produces a miniature x-ray unit called the Cool-X that has a photon output equivalent to two milliCuries, with 75 % of the flux less than 10 KeV.  Elsewhere in the product literature, the output is described as 5 milliSieverts per hour.  So, the user has to be a little careful with this thing. But rad safety issues aside, this is quite an amazing source. The product literature doesn’t come out and say what kind of crystals are used, but they may be a tantalate salt.

AmpTek Cool-X

The unit does not operate continuously. It can only generate x-rays durig a thermal cycling period, The xtal starts out cool and as it’s heated, generates the electron flux that is de-accelerated by impacting the copper to produce the x-rays. The lit gives a cycling interval of 2-5 minutes.  It is referred to as a Kharkov X-ray generator.

It’s magic.

Materials of Construction

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One of the things you have to consider when scaling up a chemical process is the composition of the wetted or exposed surfaces in the reaction vessel, associated feed piping, gaskets, and overhead vapor  spaces.  Common materials of construction subject to wetting are steel (various types), glass, Hastelloy(s), tantalum, titanium, PTFE, Viton, and various polymers found in hoses.

Metal batch reactors are subject to erosion over time. Vessel walls can be tested for thickness periodically. Glass coated reactors are very useful for their broad applicability to many kinds of reactions, but have drawbacks of their own.  Glassed vessels are sensitive to very high and very low temperatures as well as thermal gradients across the vessel wall. It is possible to crack the glass coating and have it flake away, exposing the underlying metal to corrosion.

We are all trained to do chemistry in glass reactors, but it should be pointed out that much chemistry can be performed in steel vessels. While you want to give some thought to the use of hydrogen, for the most part metal pots are well suited for reaction under neutral or reducing conditions. That is, metal hydrides, Na, carbanionic species BuLi and RMgX, alkoxides, etc., are well tolerated in wetted-metal pots.

Oxidizing or acid halide producing reaction systems are problematic for metal pots, however.  Acidic corrosive reaction mixtures can attack the wetted metal parts of the reactor system. Acidic chlorides in particular are quite corrosive to various grades of steel. It is especially problematic when you’re talking about shell and tube condensers. The tubes are often very thin for good heat transfer, leading to the possibility of the introduction of chiller fluids into the reactor if corrosion chews through the tubes.  If the chiller fluids are protic and the pot is full of MeLi, then the batch may be lost or an unplanned reactive hazard event may take place.

Condenser surfaces can be subject to more corrosion that you realize. This is the location where hot concentrated corrosive gases will condense, after all. To extend the life of the condenser, special materials of construction may be used. Tantalum and PTFE can be used when the cost is justified. With exotic materials of construction come exotic prices.

There is more to consider than corrosion.  Polymer transfer lines will generate static electric hazards via the isolation of charge on nonconductive surfaces. Tranferring hydrocarbon solvents from a drum or cylinder to a reactor through nonconductive plumbing can generate significant hazardous energy and certainly enough to be incendive. Grounded metal piping can prevent part of this problem.  However, discharging a flammable liquid into an air filled space may lead to an incendive discharge as well. It is important that all atmospheres over flammable liquids be inerted. While you may not be able to stop static discharges, you can certainly keep the fire triangle for being formed.

Operators are often alarmed by the sight of a glassed reactor with stirring toluene in it generating sparks by discharge through the glass coating.  While this may be hard on the glassing by forming pinholes, unless there is an explosive material in solution, the lack of a complete fire triangle means that the sparks cannot lead to ignition of the toluene.

Remember not to take your material to high viscosity or dryness in a large reactor. You might end up rolling your solid material into a giant bowling ball and bending your agitator shaft.  Maybe even slamming it into the reactor wall. A very expensive mistake.

Of Limited Brain Bandwidth

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At some point a person has to decide that he/she is involved in enough activitites in life. This uncomfortable world of overcommitment is where I have been for a while. I’ve come to the realization that my consciousness has limited bandwidth and that intellectual stimulus can overload it in ways that are hard to recognize. 

Having been born with lots of curiosity, I find myself piqued by a great variety of things in the universe.  The sciency stuff is obvious. But there are other things that can consume much of my capacity for attention.  It is much like an addiction to a drug. One soon becomes accustomed to a high baseline level of stimulus.  As boredom sets in,  the brain seeks greater stimulus. I can’t bear to wait 5 minutes without something to read. Cable television and the internet takes full advantage of this.

Last weekend I found myself totally immersed in the Free Electron Gas theory of metals. As I was wrestling with the math my family was out shopping and having fun. I was having fun as well, but it was of a more cloistered form. Was I being selfish? I think the answer is yes.

So, this life of intellectual pursuit can spin into a solitary life.  I like to joke that some days I’m misanthropic and other days I’m very misanthropic. That’s not exactly true, but I will say that my patience for unstimulating conversation is limited.  It comes down to the fuzzy boundary between ambition and obsession.  It is very easy to slip into a condition that is referred to as eccentric.  I can see how it happens. Maybe it is too late.

Things to notice about the disasters in Japan

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Everyone is rightfully concerned about Japan and what is to become of the region around the Fukushima Dai’ichi generating station. The quality of information by the various broadcast outlets is improving somewhat in my estimation. What the rest of the world should take note of is the stoic and highly admirable manner in which the Japanese have responded to the earthquake*tsunami*nuclear-disaster trifecta that has fallen upon them. In a US city there’d be looting and widespread felonious mischief as local criminal entrepreneurs rose to the occasion.

Another thing that I hope is noticed is the manner in which the failures initiated and propagated at the power station.  The unfortunate low elevation of the emergency generators is the obvious one.  But there is something else that is dramatically affecting how the incident propagates.  If you look at the cutaway diagrams of the plant you will see the highly compact nature of the facility.  The footprint of the buildings are quite small given the amount of equipment and processing that occurs there. In particular, the location of the cooling pools for the spent fuel assemblies is at the upper level of the structure, above the reactor spaces. 

The upper level with the cooling pools has an overhead crane that can move along the length of the facility. The fuel elements can be pulled up and out of the reactor and moved laterally into the pool.   The General Electric design is quite efficient in the use of acreage. But in the event of a major upset with fire, explosions, major radioactive material release, and structural damage, the compactness of the facility and the elevation of the spent fuel cooling pools works for prolonged incident propagation and against termination. 

The very altitude of the cooling pool spaces presents a major hurdle to taking control of the situation.  Having this problem at ground level where you could directly apply resources to the event would be bad enough. But to have it many stories above ground places huge constraints on the responders.  Designers of power plants should be thinking about where hazardous energy can be released and how responders will deal with it. Problem- all facilities design projects are constrained by severe cost considerations. Designers prefer to think about the most efficient designs, not how their brain child is going to fail.

Credible Information on Fukushima

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It is difficult to find truly informed opinion on the Fukushima reactor disaster in Japan.  The Daily Kos Community site by Richard Blair seems very credible from what I can discern.  The writer claims to be a Nuclear Power Operations-certified systems engineer in GE Boiling Water Reactors (BWRs). I have no reason to disbelieve it.

Actually, Rachel Maddow (and writers) did a very even handed presentation this evening of the basics of reactors, radiation, and nuclear power generation on her show. 

Blair (writing under the pseudonym Richard Cranium) shares some interesting insights on the Fukushima boiling water reactors. It’s worth a look.  It is part of a larger effort at information aggregation called the Japan Nuclear Disaster: Mothership.

Bug Hunt: Los Angeles

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Big, angry, armored termite soldiers from the Planet “O” land off the coast of SoCal and make an amphibious assault. Luckily for humanity they land near Camp Pendelton. Thus begins Battle: Los Angeles. 

Filmed in a documentary style, this movie follows the travails of a platoon of Marines on a mission to pick up civilians at a police station in Malibu and take them to a forward operating base (FOB) before heavy bombardment of the coast begins. The aliens take and keep the initiative early in the invasion.

The invaders aren’t misunderstood ET’s with big blue cow eyes.  These bipedal and possibly cyborgish critters are loaded with high velocity rounds and are fiendishly single-minded in their attempt to secure the planet. Aaron Eckhart plays the lead character, Staff Sergeant Michael Nantz.  Along the way the platoon picks up USAF staff sergeant Elena Santos played by Michelle Rodriguez. The casting of Rodriguez was particularly smart from the marketing perspective. Hotties with automatic weapons are irresistable to the male moviegoer. I’m thinking of Ripley making her escape from the Nostromo.

OK, guys, this is not a chick flick. It’s not especially bloody, but it is filled to the brim with male bravado and long satisfying bursts of full automatic gun fire. Wives and girl friends may be unmoved by the machinegun aesthetic. Just thought I’d mention it.

It’s not Academy Award stuff, but it is worth seeing on the big screen.

On a separate topic, for the fans of Dune, there is this link.