So there's been a huge mess on; you probably all know about it by now. Bunch of unethical corporate cowboys, gang of lawyers, Byzantine (not to say Kafkaesque) legal proceedings obsessed with letter rather than spirit, left-wing newspaper fighting back by sticking to the letter of Parliamentary procedure and making the spirit do triple reverse somersaults.
Not my field, so I'm not going to comment further on that, but I have just read the Minton Report
(PDF link) and have some comments to make about the chemistry involved.
Most of them are unrepeatable, but can be summarized as "they did WHAT? WHY? What the BLOODY HELL did they think they were doing?"
In short, they found a nice-looking process to refine their partially treated crude, decided that using an actual chemical plant and some sensible procedures was too much like work, churned all the stuff together in the hold of a ship, and then slung in some more caustic soda for good measure, presumably on the age-old pharmaceutical principle of "well, if a little bit is good for you, a lot must be much better, right?"
. After that, they separated out the bit they wanted
and threw away the rest.
"The rest" in this case consisted of a total of about 285 metric tons of foul water, naphtha, caustic soda, and mercaptans. Mercaptans, also known as thiols, are the foulest-smelling substances known to humanity. One afternoon at Cranfield, I accidentally let about 10 cc of a harmless mercaptan loose from the fume cupboard (I'd been working with them too long, and couldn't smell them any more) and the entire School of Engineering spontaneously evacuated itself. It took me half an hour and a lot of waving the MSDS around to convince the builders working on the outside
of the building that it was safe to go back to work.
When I say "harmless", I mean that it wasn't toxic, and that in those concentrations all it did was smell bad - we didn't get anyone choking and coughing, vomiting, or crying uncontrollably. That was mostly because it was a nice clear summer's day, with a good strong breeze, and it dispersed quickly. Most mercaptans will do all that, and are poisonous too; the ones released at Abidjan were. Oh, and there's another problem, too; when exposed to acid, mercaptans turn into hydrogen sulphide. H2
S isn't just the smell of rotten eggs; it's corrosive and highly toxic. UK Occupational Health guidelines allow exposure to 10 parts per million H2
S for 15 minutes. If the concentration goes over above about 20 ppm, it stops being possible to smell it, which means you breathe a lot more of it. The Minton report goes into a lot of detail on the dangers of these compounds, and the only other thing I'll highlight from there is that the waste dump is extremely
environmentally damaging as well as toxic. Burning and salting the fields does not even make the list in comparison.
And they dumped this crap right there. If you're keen on the letter of regulations, it's possible to make an argument that what they did was not illegal yet; on the other hand, that's missing the point rather. It's also possible (and wearisomely inevitable) to make the eternal "That was the blokes we hired - nuffink to do with us, guv" argument, but I do hope none of my readers will insult our collective intelligence by doing that.
Trafigura have stated in several places since then that standard handling and disposal practices were followed. This is what we technically call "an outright lie". It may be standard if you happen to be a cowboy with neither common sense nor empathy; it may be possible to argue that that sort of slapdash unconcern comes as standard in the business; it does nobody any credit to do so.
 It isn't. It made the reaction less efficient and more wasteful, and made it produce a much higher proportion of more toxic volatiles in the waste.
 Which still contained plenty of mercaptans. This procedure doesn't even get more than half of them out.