6 replies to this topic

[Kevinyun]

Hey everyone

Just wondering what the dangers are of boiling sodium hydroxide in an open mixing vessel with a lid and agitator?

The internet seems to only give me the boiling point of it but not the dangers

I'm guessing there will be a lot of steam produced and vapour and high temperatures but what other dangers are there that I may need to consider for a safe working process which involves dissolving sodium hydroxide pearls with water?

[breizh]

Danger !

PLease read this document :

http://www.jsia.gr.j...andling_01e.pdf


Breizh

[Kevinyun]

Hi Breizh

Thanks for that document, but I had already had that document printed out and I have read it. It does talk about the dangers of mixing caustic pearls with water but not when it reaches boiling point? Would the effects of it splattering, causing a mist and obviously generating lots of heat and releasing hydrogen be the same for when it reaches boiling temperature or would it be worse?

[breizh]

One of my operator has got burn ( 2nd degree) during such operation ! It is difficult to control the rate of introduction of the pearls and if you are using hot water there is a huge risk of boiling , meaning mist of caustic going everywhere , content of the vessel overflowing ......

from Dow Chemical Handbook :

The addition of caustic soda to liquid will cause a rise in temperature.
If caustic soda becomes concentrated
in one area, or is added too
rapidly, or is added to hot or cold liquid, a rapid temperature increase
can result in dangerous mists or boiling and spattering, which may
cause an immediate violent eruption.



Hope I've been clear enough to support your query.

Note : during this kind of operation , full set of PPE is required ( goggles , facial mask , apron , gloves,..)

Breizh

Edited by breizh, 08 August 2012 - 11:06 PM.

[Art Montemayor]

Kevin:

For everyone’s sake – especially for your safety and the safety of those under you and around you - during a solid caustic mixing operation, please heed Briezh’s advice and warnings. Do not take the mixing of solid caustic lightly or with too much confidence.

I have seen what caustic soda can do to human tissue and it isn’t pretty. Caustic brutally attacks and consumes human tissue – especially those areas such as the eyes, face, and hands. It is corrosive and acts rapidly, causing considerable pain and suffering. The damage done to human tissue is often irreparable. Ocular burns can cause complete loss of vision. This is bad, bad, nasty stuff.

I presume you are a young engineer; otherwise, you would not hesitate in taking all precautions with this stuff. We old timers know the inherent dangers and lack of control when handling solids. Solids still predominate within the chemical industry as the most difficult form and phase of a compound to manage, control, and measure. Transporting solids is awkward and full of problems – as is the metering out of solids, even when they are in the “pellet” form. You will always get the inevitable DUST, POWDERING, SPILLAGE, and ATTRITION. There is no way to avoid the attrition and dusting. What appears as a simple, old-fashioned manual handling chore turns out to be a potential nightmare if you are not careful and prepared to handle the worse-case scenario.

I would not undertake this kind of assignment lightly nor would I attempt to do it without complete, redundant, safety procedures and equipment. I certainly would not boil a caustic solution in an open vessel or one that wasn’t specifically designed and out-fitted to carryout this procedure with total safety reviewed, checked, and confirmed.

Good luck – and stay safe.

[kkala]

In addition to previous posts, please refer to attached "NaOH Handbook.pdf", page 19 - "Dissolving anhydrous caustic soda". Reported "spurting" is understood to have some similarity to boil over for stored fuels containing water, potentially resulting in dangerous situations. Unfortunately preventive measures are qualitatively mentioned (not quantitatively). Enquiries from specialized vendors could be a way out, to obtain homogenization of the liquid in the tank and operation temperature lower enough than normal boiling point.
Rise in temperature could be quantitative predicted though (Graphs 1, 5, 6 in attached pdf file)

Attached Files

•  NaOH Hand book.pdf   689.8KB   51 downloads

[Dipankarc84]

Kevinyun,

I have worked in a Caustic plant and I can tell you for sure that you do not want to do anything funny with caustic. The mist that you mention would start to cause eye burns and caustic causes severe skin burns. Even 30% concentrated caustic solution can put you out of work.