Sciencemadness Discussion Board

Recover Tungsten From Tungsten Carbide Scrap

mdkothari - 17-6-2011 at 23:37

hi
can anyone suggest a way to recover tungsten (as metal or any salt) from tunsten carbide waste.
regards

bbartlog - 18-6-2011 at 05:36

Sodium hydroxide solution and air should give you sodium tungstate in solution. But you might want to look at patents for this. If you're dealing with sintered tooling inserts, then binders used to cement the tungsten carbide particles (molybdenum or cobalt or what have you) may also dissolve and I have no idea whether you are aiming for a selective process that would leave that stuff behind.

mdkothari - 19-6-2011 at 21:39

thanks
i am working here with different method in the lab. will update soon

a_bab - 19-6-2011 at 22:22

A long refluxing with con. nitric acid will get the Co matrix in solution. The W is in the form of WC as a fine powder.

froot - 20-6-2011 at 01:35

Quote: Originally posted by mdkothari  
thanks
i am working here with different method in the lab. will update soon


Please do.

Wiki mentioned that WC is only attacked by F2 or HF/HNO3 mixture, stuff I don't want near me.

Wiki also mentioned that WC has been considered as a substitute for Pt as a hydrogen catalyst. How true is this? If so then that would bring a home fabricated hydrogen electrode right down within my realm of possibilities.

CaliusOptimus - 25-6-2011 at 12:32

ive got an addition to the question.

in the manufacture of carbide tooling, WC grinding sludge is generated as a byproduct. it is a mixture of:

WC powder (plus a cobalt binder, usually around 10%)
grinding coolant (oil or water based)
Al2O3 from dressing sticks
a small amount of diamond and bonding material from the grinding wheel
possibly organic and other contaminants

how would one remove the tungsten from such a mixture?

[Edited on 25-6-2011 by CaliusOptimus]

not_important - 25-6-2011 at 14:21

Wash with non-polar solvent to remove oils, then with water to pull water soluble/miscible coolant and trash. Hot HCl should remove the cobalt matrix, the higher cobalt oxides reduce the HCl forming CoCl2 and water and some Cl2.

To get the tungsten consider

http://hdl.handle.net/10204/529
Quote:
Aliquots of powdered tungsten carbide were dissolved in a solution of 5% aqua regia in 30% hydrogen peroxide. Complete dissolution was usually achieved within 10 min. The accuracy of the method was assessed by the analysis of certified reference materials, secondary reference materials and matrix spiking. The method was successfully applied to commercial type samples with differing compositions. Slightly more emphasis was placed on the measurement of vanadium, since no information on the measurement of-this element in solutions of tungsten carbide, by ICP-OES, has been published. The purpose of the study was to provide an alternative, more rapid and less expensive method of dissolving tungsten carbide–cobalt using only nitric acid, hydrochloric acid, hydrogen peroxide and tartaric acid.


Al2O3 and silicates are reasonable resistant to non-fluoride-containing acids, and will remain behind.
Quote: Originally posted by froot  
...
Wiki also mentioned that WC has been considered as a substitute for Pt as a hydrogen catalyst. How true is this?...


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