Category Archives: Safety

Thermochemical Snipe Hunt

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Spent the better part of the day hunting snipe in the chemical literature. I’ve been looking for some English language literature relating to the Yoshida explosive potential correlation between DSC heat of formation and DSC onset temperature. I have some sketchy relationships from Yoshida in Chemical Abstracts CAN 108:58900 –

Shock Sensitivity = log (QDSC) – 0.72*log(TDSC-25) – 0.98

Explosive Potential = log (QDSC) – 0.38*log(TDSC-25) – 1.67

QDSC is the magnitude of the exotherm as measured by DSC (presumably in J/g, not J/mol), and TDSC is the onset temp also determined by DSC. A separate reference suggests that compositions with EP>0 are potentially explosive.

I want some better grounding in the assumptions going into the correlation before I pony up my own results. This is potentially a very useful relationship in reactive hazards work and something I can do in the lab myself.

It’s a pity I do not speak Japanese since much of the cited work is in Kogyo Kayaku and in Japanese.

Scheiss!!

Ever pondered the merits of mixing up a batch of N5 salt? Polynitrogen chemistry. Yikes. Check out this link (rather large).

Bronx Cheer for National Geographic

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After supper last night I parked in front of the tubule and switched on the Discovery Channel. There was an intriguing program on the Cueva de los Cristales (Cave of Crystals) in Mexico. The Naica mine has become famous for its gigantic selenite crystals (calcium sulfate). National Geographic filmed a program on these wondrous crystals and it has been broadcast on the Discovery Channel.

What has raised my ire on this is not the production value. As usual, the cimematography was superb. What is disappointing is the story they chose to tell.

What I have noticed in the public science programming world is a particular weakness that quietly infects writers, directors, and producers. The weakness has to do with the fear of boring their audience. Rather than risk a pandemic of somnolence, writers kick up the script a notch with undercurrents of intrigue and a suggestion of danger for the intrepid parties crawling in the muck or harassing gators.

That’s fine. It never hurts to plan for short attention spans in the audience. But what suffers is a sense of proportion. When the focus shifts from the subject of the expedition to the members of the expedition, the program crosses the line into the tawdry world of show business.

Yes, it is quite hot in the cave. Yes, heatstroke is an issue to be wary of. But, what about the crystals?? What are they made of? Where is the water from which they were precipitated from? How does crystallization work?

And, where is the chemist on the team? National Geographic brought together a geologist, a planetary astronomer, a nuclear physicist, a biologist, and a few others who were not identified. This is a common omission on the part of people outside of the chemical sciences. Nobody knows what the hell we do!

For the showbiz effect, they brought in a planetary astronomer, Dr. Chris McKay, to examine the cave for possible implications on Martian exploration and the Evolution of Life. To media people, science equals- 1) Space Science, 2) Medicine, 3) Computer Science, and 4) oh, did I say Space Science?

It turns out I used to know Chris McKay. He was a TA in an astronomy course I took at the University of Colorado ca 1978. He was a geat guy and, unlike other misfits misanthropes bed wetters grad students in the astro/geophysics program, an attentive and caring instructor. He was (and is) a true believer in space exploration. We spent a long and chilly evening together in the Sommers Bosch Observtory at CU manually guiding the 24 inch telescope on a guide star for some lengthy time exposures of a string of galaxies. We used 3×5 Tri-X plates hypered in H2.

This showbiz reflex is a chronic condition and I am sorry to see National Geographic succumb to it.

Calamity, Interrupted

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JOC will no longer appear in my mailbox. I decided to let go of this icon of my earlier years. Organic Process Research & Development will “arrive”, but this time I have taken a web subscription for $40/year. In the interest of domestic harmony, the rate of paper accumulation will drop somewhat.   The trouble with this form of access to the literature is that I can’t take a journal to the local taco joint where I lunch on occasion.

The recent subscription, the Journal of Loss Prevention, is quite interesting. Lots of articles on the dynamics of explosions and fires as well as studies on calamaties, disasters, and general industrial mayhem. I can dig it.

Both imagination and knowledge are an important part of chemical process safety. A process safety person should have a solid chemistry background to grasp what is happening in a reactor or piece of equipment. Imagination comes in to play when trying to anticipate failure modes leading to initiation and propagation of incidents.

It isn’t possible to anticipate all possible failure modes in a chemical process. And not every failure leads to an incident or casualty. What is possible is to collect as much information as you can for a group to do a process hazards analysis.

A properly facilitated group can unearth many possible failure modes and root causes. Once identified, an effort to remove initiation sources or uncouple possible propagation pathways can be made. The first and best goal is to eliminate a hazardous condition. Management and engineering controls should always be secondary to elimination of a hazardous condition. 

AIChE is a great source of information for process safety.

Update:  The web subscription is quite agreeable to use.

Gold Refining with Borax

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According to the GEUS, the Geological Survey Office of Denmark and Greenland, it is possible to concentrate and isolate gold from the ore using borax and charcoal. This method has the immediate benefit of making mercury “redundant” in gold isolation.

Extraction of gold by amalgamation with mercury is a simple means of producing metallic gold in the field.  After contact with gold enriched ore, mercury is evaporated into the air by direct application of a torch flame to the puddle of metal leaving purified gold metal.

It is thought that there are millions of miners who scratch out a subsistance living working a small patch of ground for gold. It’s called small scale mining. In the course of this activity, environmental contamination can accrue to the immediate area as well as the watershed at large. Sadly, the toxicological insult to the miners from exposure to mercury vapor can be severe.

This method is an inexpensive and simple alternative to the mercury process. Perhaps the chemistry community has something to contribute by way of education or improved methods of extraction.

8/25/10  Update.  I have revisited this post and am compelled to comment further.  While I am unable to offer a good chemical explanation for the effect of borax on gold ore, I can say that the use of borax as a flux  for smelting goes back to the 19th century during the American gold rush period.  The process described in the link appears to be a smelting process for enriched ore containing elemental gold, as opposed to sulfide, or sulphuretted ore. The function of a flux is to modify the flow and phase separation properties of host rock so as to partition away from the gold phase or layer.  In other words, a flux modifieds the slag to help the gold to separate cleanly from the rock.

Fissile Molten Salt Reactors

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Like it or not, the world is fitted with a web of nuclear power infrastructure. And, like it or not, we have inherited the chore of managing nuclear materials and industries from preceding generations. The question that begs to be answered is, how should we go forward with this legacy of nuclear power technology? Do we plod along maintaining  the status quo? Do we replace aging nuclear plants with non-nuclear facilities? Or, do we ramp up with more nuclear plants?

On the pro-nuclear side, alternative reactor schemes are surfacing.  Reactor designs that have been proposed for years are showing up on the internet and into the daylight.

One intriguing design utilizes a fissile molten salt that is circulated through a moderator assembly and cycled through a heat exchanger. In this scheme, the fuel is also a working heat transfer fluid. It is called a liquid fluoride reactor.  Many kinds of molten salt compositions are possible, but one is composed of (72 LiF, 16 BeF2, 12 ThF4, 0.3 UF4).  The designs I’ve seen use continuous fuel processing to keep an optimal fuel composition in use. The reactor described in the previous reference has a negative temperature coefficient, meaning that the fuel becomes less reactive as the temperature rises. This is an important safety attribute.

There is no point in a recital of the technical details here. The reader can follow the links if interested.

US Airways Splashdown on the Hudson

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The Hudson River touchdown of US Airways flight 1549 has been called a miracle by some folks. How these folks would describe the ingestion of a flock of birds in terms of miraculous phenomena has not been disclosed. Whatever it was, the aircrew certainly performed admirably.

If you look at a map of the flight path and note the timing, one minute after the birdstrike the A320 had descended from 4000′ to 2000′. At this phase of flight 1549, the airplane is heavy with fuel, baggage, and people. They are configured for climbout and are navigating in congested airspace at low altitude.  At least one of the pilots has his head on a swivel watching for traffic while the other is monitoring flight control systems.

After the birdstrike, there would be some seconds of confusion where the pilot and first officer would have to analyze the warning annunciators as well as what story the flight instruments are telling them. Loss of power on climbout means a prompt loss of airspeed. Here the pilot and first officer would coordinate their cockpit duties. One pilot will concentrate on flying the airplane while the other would, for instance, focus on an engine restart, declaring an emergency with the tower or TRACON, notify the cabin crew for emergency procedures, etc.

While the pilots are determining what kinds of flight controls they have to work with and what other failures may be unfolding, they have to establish a standard airspeed that will minimize their decent rate. This gives them more time in the air and correspondingly, more landing options.

An airplane does a coordinated turn by banking the wing and tilting the lift vector in the direction of the turn. As you tilt the wing, the force vector acting against gravity becomes smaller and without coordinated input from other controls and a bit of power, the airplane will begin to sink.

The point is that when you bank an aircraft during a deadstick glide, you will increase the sink rate. Looking at the map, the pilot could not afford to lose anymore altitude by attempting to make a gliding turn to Teterboro to get lined up with the runways. They had no choice but to continue straight forward along the direction of the river and hope they could land in the water without dipping a wing and cartwheeling the airplane.

I’d say the aircrew made a series of good decisions.

Chemist Alert! NFPA 400 to be posted in May 2009.

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The National Fire Protection Association (NFPA) is an international nonprofit organization dedicated to the prevention of fire related incidents. The have recently pitched a set of regulations as NFPA 400 pertaining to the storage of hazardous materials. The comment period is long over and soon the rules will be issued as a published document.  While the NFPA is not a regulating body, their rules are widely adopted by government organizations and promulgated.

If you have not taken the chance to review some of these documents, it is well worth your time as a chemical professional to do so. Why? Because the practice of chemistry is being dramatically necked-down in terms of the kinds of chemistry that can be practiced and the manner in which materials are stored. Not only is your local fire marshal packing a stack of NFPA based fire codes, but a whole host of federal regulators are armed with regulations from Homeland Security, EPA (i.e., TSCA), DOT, REACH, and an alphabet soup of regulatory coverage aimed at every conceivable substance.

Organizations that oversee chemical operations include the chemical industry, hospitals, agriculture, mining, and academia. All organizations are under the obligation to provide a safe workplace for the employees. It makes sense to minimize employee exposure to risk. But the web of applicable regulations for any given chemical operation is expanding by the day.

Not only is an organization obliged to conduct business in compliance, but quite often there is the requirement of self-reporting of noncompliance. An organization finding itself out of compliance is an organization in need of legal representation. The nuances relating to most any kind of regulation are such that your average company president will generally be unwilling to settle the malfeasance with the regulatory agency without the help of an attorney. This is the point where a jet of cash starts flying out of the company coffers.

So, the question of the effect on academic chemistry arises.  Academic chemistry departments are seeing increased coverage under the regulatory umbrella as well. Should academic research labs have some sort of dispensation given the nature of the activity? Given that OSHA regulations may not be applicable to students, academic labs are already under somewhat less scrutiny. More to the point, how much government intrusion should researchers accept in relation to the kinds of chemicals they work with and store and the kinds of risks that are taken during research?

This is important for a very good reason. The issuance of proposed rules by organizations like NFPA results in regulatory pressures that eventually find their way to individual researchers. But the researchers don’t hear about it directly from NFPA. The University Health and Safety department hears about the regulations (or guidelines) and they apply requirements on chemistry departments. Faculty being faculty, they’ll perform a gritching ritual and eventually comply.

Generally, the arrival of new regulations results in new constraints. The end result is that the department has to spend more to operate the labs and students receive less experience with interesting chemistry. This whole unfortunate trend of increasing government oversight of all things chemical will eventually neuter US chemical education and industry leaving a bland and uncompetitive culture averse to risk.

I hate to be critical of fire safety people. But I also hate to see chemical education and research hamstrung by well intended parties who have devised highly detailed and extensive rules that will seep into every aspect of the chemical sciences. I am aware of absolutely no pushback of any kind when it comes to this matter.

Flux-O-Links

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The US Nuclear Regulatory Commission website offers a downloadable set of documents pertaining to Fire Dynamics along with a few spreadsheets and loads of worked problems. The set of documents is quite well done in my estimation and is entirely suitable for we industrial chemists. My operating principle is that it never hurts to keep learning about fire phenomena when you work around flammable materials.

Gotten a little rusty in your welding theory?

An affordable spectrum analyzer is just what a fellow needs for the radio observatory.

Need pure Astatine, see p 19.  Light up the accelerator and dial up the proton current.

Thermite Sparking

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Until recently I was blissfully unaware of the possibility of something called Thermite Sparking. It is a variety of the classic Thermite reaction, only it can happen inadvertently in the workplace by mechanical friction.

Thermite sparking is a circumstance wherein an aluminum part smartly strikes an oxidized iron component generating a momentary and highly localized spot of very hot metal. Normally, the thermite reaction is limited to the small mass of material in the impact zone and does not progress further.

What is useful to know is that aluminum and iron together constitute a sparking pair of materials and could serve as an ignition source for flammable liquids and vapor in the area. An aluminum cart or component could suffer an impact while in motion and provide an ignition source for a fire.