finishing.com -- The Home Page of the Finishing Industry
A website for Serious Education, promoting Aloha,
& the most FUN smiley you can have in metal finishing

HomeFAQsBooksHelpWantedAdvertiseForum
topic 3659

Phosphate removal from chrome solution


Tue -

Does anyone know how to remove phosphates from a standard chromic acid plating solution? We are trying to remove the phosphates in our treatment system prior to chrome reduction and recovery of the chrome as a metal precipitate. I understand there's a relatively simple chemical process but I haven't been able to figure it out. (The phosphates are a source of phosphorous in the recovered chrome precipitate. Phosphorous is very detrimental in the recycling of chrome back to the stainless steel industry).

Jim Sullivan
metal recovery - Paterson, New Jersey


(1999)

That's tough. Chrome solution is pretty acidic. I would say your best bet would be to neutralize most of the acidity with lime or magnesium hydroxide, then drop the phosphate with aluminum sulfate. With experiment, you may be able to find a level of neutralization that will still leave enough acid for the metabisulfite (I presume that's what you're using) to work.

If not that, then the only thing would be to neutralize *all* the acidity, drop the phosphate with Ca, Mg, or Al, then reacidify the waste for the reduction step. Or, live with the problem.

dave wichern
Dave Wichern
Consultant - The Bronx, New York


(1999)

Why wouldn't you reduce and precipitate the chrome, allowing soluble phosphates to just wash away? I haven't done this, as I've never seen a problem of phosphates in chrome, but it sounds like it would work.

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



This public forum has 60,000 threads. If you have a question in mind which seems off topic to this thread, you might prefer to Search the Site

ADD a Q or A to THIS thread START a NEW THREADView This Week's HOT TOPICS

Disclaimer: It's not possible to diagnose a finishing problem or the hazards of an operation via these pages. All information presented is for general reference and does not represent a professional opinion nor the policy of an author's employer. The internet is largely anonymous & unvetted; some names may be fictitious and some recommendations may be deliberately harmful.

  If you need a product/service, please check these Directories:

JobshopsCapital Equip. & Install'nChemicals & Consumables Consult'g, Train'g, SoftwareEnvironmental ComplianceTesting Svcs. & Devices


©1995-2017 finishing.com     -    Privacy Policy
How Google uses data when you visit this site.