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Wed Jan 30, 2019, 02:14 AM

So my kid is taking a Chemical Engineering course called Unit Operations and the Professor asked...

...the class to contemplate a case where a customer who had been purchasing hydrochloric acid, a side product of their process, went out of business. The professor noted that environmental regulations prevented the release of the material and that waste disposal for it costs were high.

"What do you do?" the professor asked.

Someone raised his hand and said, "Pay a lobbyist to change the environmental regulations!"

Everybody laughed, including the professor.

(My son, who says that the class consists of fellow students who have a great sense of humor.)

Everybody laughed...everybody laughed...everybody laughed...

I explained to my son that this is a very real problem. Most of the world's waste hydrochloric acid waste is deep welled.

"Wouldn't that dissolve the rock and cause problems?" my son asked. "Couldn't that cause collapse?"

"Um...um...um..." I said, and went on to apologize on behalf of my generation to his. "These are the sorts of problems you are tasked to solve," I said. I apologized again.

This, by the way, is the chemical reaction that produces polysilicon:

HSiCl3 → Si + HCl + Cl2

The solar industry, which is a trivial industry, producing trivial amounts of energy despite more than half a century of mindless cheering for it, is a huge consumer of the explosive and corrosive gas that is the reactant in this chemistry, trichlorosilane.

Have a nice "hump day" tomorrow.

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Response to NNadir (Original post)

Wed Jan 30, 2019, 02:55 AM

1. Is it really that expensive to neutralize it? Don't we create like a bajillion lbs of base ...

Per year? Various compounds that could be used to turn HCL into water and salt?

Then again ... I guess a lot of those reactions also produce ... CO2, huh?


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Response to mr_lebowski (Reply #1)

Wed Jan 30, 2019, 10:32 AM

2. Limestone is the cheapest base, and yes, it produces CO2.

That's what the deep wells are for -- to save the cost of even mining the limestone.

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Response to mr_lebowski (Reply #1)

Sat Feb 2, 2019, 08:35 AM

8. Almost all of the base we produce is so produced by electrolysis. Mercury electrodes...

...have generally been used, although in recent years new technologies have begun to displace these. Where sodium chloride is the source the reaction is 2NaCl + 2H2O <-> 2NaOH + H2 + Cl2.

In general this a poor way to make hydrogen, and on scale it's trivial, as trivial as the solar industry is in terms of energy: Less than 1%

The chlorine is generally used to make bleach: 2NaOH + Cl2 <-> 2NaOCl. The use of mercury electrodes resulted in bleach being a minor source of mercury in water, trivial in comparison to coal fired power plants, but significant all the same.

It is also used chlorinated chemicals, many of which have been proved to be persistent pollutants, most notably PCB's, and of course the now (almost) banned CFC's, and in addition (historically) DDT. Historically many carbonates, diethyl carbonate and dimethyl carbonate, as well as isocyanates (including I believe methylisocyante at Bopal) are made with phosgene, COCl2, which is made by reaction of carbon monoxide, usually from the partial oxidation of dangerous natural gas, and chlorine gas. (Phosgene is also used in the pharmaceutical industry; I've had the pleasure of working with it extensively early in my career.) The largest use for chlorine gas is probably PVC, polyvinyl chloride. It's synthesis also releases HCl.

Reactions making carbonates or isocyanates release HCl, often far from the electrolysis plants. The combustion of vinylchloride in municipal waste also releases HCl, although this is generally vented to the air.

To the extent that these chemicals persist, they represent a disequilibrium with respect to NaOH. However the requirement for electricity, given the grotesque and expensive failure of so called "renewable energy" to make even a trivial dent in climate change, means that this electricity is mostly carbon based; as I frequently point out, in 2017 alone, the use of dangerous natural gas grew nearly four times as fast as the (sqaundered) multi-trillion dollar solar and wind industry combined in units of energy - not that the proponents of these cockamamie schemes understand energy at all.

As your other response indicated, it is true that carbonates such as limestone can be utilized. Deep welling can be into carbonate formations, as noted in the other response. This is, I suppose, rather like what is proposed as sequestration, but the carbon dioxide will eventually leak, and may actually kill people directly, as happened famously at Lake Nyos. With highly drilled rock, future generations can expect multiple Lake Nyos type events, which is another load of contempt this generation of consumers has dumped on them.

My curiosity piqued by writing this post, I came across an interesting and fun paper that I may ridicule in this space, which is a proposal to fight climate change by deep welling billion ton quantities of HCl. I haven't actually read the paper yet, but on its face, and from the abstract, it blows my mind that anyone would ever consider this. (More serious NaOH based carbon dioxide capture systems are well known, my current favorite being Dr. Heather Willauer's proposal to make Naval Jet Fuel out of seawater, with seawater carbonate as the carbon source. This is a marvelous technology that I hope will pan out.)

Sorry to get to your good question last. I've been stretched for time.

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Response to NNadir (Original post)

Wed Jan 30, 2019, 10:44 AM

3. HSiCl3 is produced from silicon alloys and ... HCl, is it not ?

It seems someone would have thought of generating the HSiCl3, purifying it, and decomposing it in the same plant, so the HCl could be recycled. I suspect the HSiCl3 is first made in a crude form, then shipped to a separate location where the purification is done. Crude, dirty, bulk scale in one location, refinement in the other, but it would seem that could be changed with a reasonable effort.

Since we're producing megatons of Cl2 by the chloralkali process, why not investigate using HCl as the electrolyte instead ? No alkali would be produced, but the valuable products H2 and Cl2 would find plenty of uses. (OTOH, one should avoid electrolytic processes as energy sinks, especially for FFs.) Perhaps the Deacon process could be modernized ?

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Response to eppur_se_muova (Reply #3)

Fri Feb 1, 2019, 04:17 AM

6. Yes, it is. The initial reduction of SiO2 is carbothermic, usually with anthracite coal or coke.

Since it's coal or coke are usually contaminated with other elements, and because under these conditions, in a furnace in excess of 2000C, a certain amount of the wonderful refractory SiC forms, it is necessary to purify the crude silicon.

Silicon is generally resistant to attack by mineral acids with the exception of HF, but at elevated temperatures, it is attacked by gaseous HCl to form trichlorosilane, a liquid which is then distilled to purify it.

Trichlorosilane is explosive, and an explosion in Japan instanteously killed more people that were instantly killed by Fukushima's radiation releases, albeit not nearly as died in the earthquake from drowning, not that anyone is concerned with the safety of living on shorelines and thus proposes to ban coastal cities. Explosion at Mitsubishi polysilicon plant in Japan causes deaths

Generally risk is qualified in terms of DALY's, disability adjusted lost years, which accounts for how fast something kills victims of exposure.

Mid-career, I was involved heavily in the manufacturing side of the pharmaceutical industry, and as such toured chemical plants all around the world and became familiar with the general approach of the chemical industry.

It would seem, as you correctly note, that the output of the decomposition of trichlorosilane, pure silicon - but generally with some remaining impurities which often require zone refining via melting for further purification for use in chips - that HCl (along with chlorine gas) is produced in this reaction, and thus that the HCl could be recycled. However - and I'm speaking here not from direct knowledge, but by assumption - several factors may impact this. As noted, even distilled, the trichlorosilane might still contain minor impurities, hydrogen sulfide for example, other halogen acids such as HF etc, and the recycling might impact the purity, over time of the trichlorosilane. Trapping the gas to drive equilibrium may be into water, in which case it becomes problematic to reconvert the HCl into gas. The chlorine in the waste gas stream may be difficult to separate. Most importantly, the equipment may be fairly expensive - a common steel reactor is not going to be able to handle gaseous HCl at high temperature.

It's worth noting that the recent recalls of the "sartan" drugs apparently took place because Huahai decided to recycle solvents, leading to the accumulation of carcinogenic nitrosoamines in the product.

In the chemical industry, people speak of being "basic" in a commodity. A company can be "basic" in phosgene if they make their own phosgene on site from carbon monoxide and chlorine gas, and use the phosgene to make, say, isocyanates. Another option however is to buy phosgene in cylinders.

I suspect that the Huahai plant included specialized equipment utilized to make tetrazoles, which is not necessarily trivial chemistry, and probably they were "basic" in azides.

Whether or not to be basic in a commodity is described as a "make or buy" decision. My guess is that for the silicon commodity, basic plants for the manufacture of crude silicon, and then trichlorosilane, and then purified silicon plants using zone refining and finally chips or solar cells themselves are often far apart.

I've worked on projects in which oncology drugs were manufactured using over 25 steps. As I was familiar with the process, I had a pretty good sense of where the stuff was made. Intermediates from France, Germany and Japan were all shipped to the United States to make major intermediates which were then all shipped to Ireland to a high potency isolation plant - an expensive plant - to make about 10 kg of the drug, which, owing to its potency, was the world supply.

All this manufacturing was performed because the main other source of the drug was the bark of a rare tree in China, giving China control over the world supply and putting pressure on the tree population.

The reason for doing this was not to save energy and be energy efficiency. It was because it involve multiple specialized plants with specialized capabilities and experience in certain kinds of reactors.

I suspect that this situation is very similar in the semiconductor/solar cell industry.

Chemical plants, and the materials that go into them are often very expensive, and in order to maximize their economic viability, they need to run at high capacity, meaning pretty much that they have to handle all kinds of projects, exhibiting flexibility.

HCl is a cheap commodity, and often, frankly not worth recovering. Often it's cheaper to dump it, or otherwise get rid of it, than to build a plant to recycle it.

While looking into this a little bit, after writing this post, by the way, I came across a 1970's description and listing of deep welling chemical disposal sites in Alabama. If you're interested, drop me an email, and I'll send it to you.

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Response to NNadir (Original post)

Wed Jan 30, 2019, 10:51 AM

4. Wrong answer

The company you used to sell it to has gone out of business... but that likely means that one of their competitors now has more business from picking up customers from the one that went under. Sell to them.

Alternatively, the stuff sells to the public at $25/L. Open up a subsidiary and sell it direct for 25% less than the competition.

IOW - It's only "waste" when it has no market value. Losing a customer doesn't mean that a marketable chemical becomes "waste".

You of all people should recognize this from debates re: the disposal of nuclear materials that other reactor designs could use as fuel.

I explained to my son that this is a very real problem. Most of the world's waste hydrochloric acid waste is deep welled.

Not exactly. It's injected intentionally as part of the oil/gas production process (clearing out base materials clogging wells)... but IIRC, the largest portion of the market is PVC manufacturing.

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Response to FBaggins (Reply #4)

Thu Jan 31, 2019, 04:34 AM

5. Nuclear materials, radioactive and other wise are high value added materials.

A price I've seen somewhere for pure isolated plutonium using current (Purex) technology is on the order of $1000/kg.

This is actually a very low price in terms of energy, since a kg of plutonium fully fissioned represents 80 trillion joules, the equivalent of 680,000 gallons of gasoline (@ 120 million joules per gallon) and thus represents a price of less than one cent per gallon, gasoline equivalent.

By appeal to Sherwood plots, given its concentration in used nuclear fuel is on the order of 1%, one might easily imagine that this price could be very close to two orders of magnitude lower, but the added cost is probably associated with the toxic mysticism of anti-nukes and their bizarre and immoral calculation that the risk of death of anyone one person from radiation, justifies thousands of deaths from dangerous fossil fuel waste.

Also by appeal to Sherwood plots, I've estimated that the price of pure technetium metal should be on the order of $50/kg. Since rhenium at current prices runs at about $2800/kg, and since technetium, owing to the lanthanide contraction is a very close analogue of rhenium, and can perform all of the the functions of rhenium nearly as well and sometimes better (as is the case of technetium catalysts in the Meerween-Verley-Pondorf oxidation), the isolation can save huge expense. (I have been very interested in technetium superalloys, particularly refractory and chemoresistant tungsten for nuclear energy applications. The addition of technetium (or rhenium) to tungsten greatly increases the machinability of this refractory element. Some of these alloys were prepared in the 1960's and they are very, very, very cool.)

HCl, by contrast, is well under a buck a kilo. As is the case with glycerol - a compound with tons of uses - from the so called "renewable" biodiesel industry, the cost of shipping it seldom justifies the price it will command at the point of sale; often one has to lose money to do this. Despite many elegant schemes to utilize it, for example in the synthesis of acrolein, or (my favorite) soketal, it is still most often land filled.

In your assumption that one needs only to find the competitor who drove the previous customer out of business, you have missed the point. If the plant is located in Arkansas and the competitor is in Malaysia, it makes no sense to approach that potential new customer.

In addition you have not considered the possibility that the bankrupt company was driven out of business by a process change. My curiosity piqued by the three responses in this thread, I took a quick superficial look at actual waste HCl issues recorded in industrial journals. Even where waste HCl is utilized (recycled) there have been many process changes involving it. For example, HCl can be obviously converted to chlorine gas, which is done where its economically viable. The most widely utilized process is straight up electrolysis; however there are also chemical procedures for the oxidation of HCl to chlorine gas. Since electrolysis is energy intensive and requires huge losses of energy, one can easily imagine a chemical process replacing the electrolysis process, wherein the electricity supplier will face reduced demand.

I'm a regular reader of the journal Energy and Fuels, which has all kinds of disturbing articles about EOR and EGR, Enhanced Oil (or Gas) Recovery - fracking. I generally avoid actually reading EOR and EGR papers unless I'm in the mood to get sickened, since I oppose the use of all dangerous fossil fuels. From those whose abstracts I've scanned, or felt I just had to read to get a feel for how unimaginably insane this all is - I wrote a post in this space about a particularly odious approach using perfluorinated organics - I haven't seen HCl, but it makes sense, since many oil reserves as I understand it are found in carbonate rocks. If it is indeed so used, it's easy to see why oil and gas extraction can cause surface collapses and earthquakes, which was the point.

Thanks for your comment.

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Response to NNadir (Original post)

Fri Feb 1, 2019, 09:26 AM

7. "The solar industry, which is a trivial industry," LOLOLOLOLOLOLOL!

It's booming worldwide.

Nuclear is not.



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Response to jpak (Reply #7)

Sat Feb 2, 2019, 12:03 PM

9. It can be both booming and trivial

Growth rates continue to be impressive (in absolute terms, if not in terms of what has been predicted here)... but the total industry size remains trivial.

As an example - the total global PV market is comparable in size to the market for servicing gas turbines.

It's even relatively trivial just compared to renewables in general.


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Response to FBaggins (Reply #9)

Sat Feb 2, 2019, 01:15 PM

10. There's a good reason why wind contributes more than solar

It's because it doesn't matter if a utility has a field of them or you have some of them on your house - a panel generates the same amount of electricity (maybe a utility invests in a tracking system to increase output where an individual would usually just install them on the roof).

When someone installs solar on their house, labor is a significant part of the cost. The payback is long term and since people move so often, it's hard to justify the expense. Calif has taken a step in the right direction with requiring all new houses to have solar - that reduces the labor part of the cost. Germany has incentives that encourages individuals to buy solar and PV contributes over 6%. Calif is about 10%. Is that trivial? I would agree it's not a lot, but I think it's not trivial considering PV works best during peak demand periods.

Utilities have an advantage with wind, mainly due to this fact >>> doubling the blade diameter cubes the output. It's is the driving force behind the development of ever increasing size of windmills.

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