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Topic: Odd composition data  (Read 1616 times)

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Offline Brennie

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Odd composition data
« on: February 23, 2017, 07:49:36 AM »
I was making a base and precious metal bearing cyanide solution by dissolving among other salts Potassium tetracyanonickelate(II) hydrate into demineralized water.

Immediately after making the solution a sample is drawn and analyzed using atomic adsorption spectrometry. The problem Im having is that the initial concentration for Nickel in solution, which is about 90 ppm differs form later solution analyses. The process Im putting it through aims to precipitate the Copper and Nickel form solution. Later analyses after only adjusting pH with sulfuric acid and adding NaSH however reads nickel concentration of around 110 ppm, the errors of which are too large to assume any error in the instrument.

To me this only makes sense if the Potassium tetracyanonickelate(II) hydrate never dissolved completely and under most of the experimental conditions dissolved completely. But then these analytical salts are used to make these types of solutions often, and I cant find other reports of a similar problem.

I know I'm leaving out a lot of detail, regarding the other salts and chemicals used to make up the solution. I just need other takes on what could be causing the weird nickel concentration results.

Offline AWK

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Re: Odd composition data
« Reply #1 on: February 23, 2017, 03:17:29 PM »
Nickel complex is soluble in water. Do you know an exact content of water in this salt? Did you takaen it into account?
AWK

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