Hydrometallurgy: Leaching in Heap, Vat, CIL, CIP, Merrill–Crowe, SX Solvent Extraction

Hydrometallurgy: Leaching in Heap, Vat, CIL, CIP, Merrill–Crowe, SX Solvent Extraction 2017-04-04T06:57:36+00:00
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Sodium Cyanide (NaCN) (10 replies and 6 comments)

biteyaboy
1 year ago
biteyaboy 1 year ago

Is there any method to check either sodium cyanide is expired or still OK? If yes what is the procedures?

Kallie
1 year ago
Kallie 1 year ago
1 like by Cyanide

Yes just do normal titration for sodium cyanide.

biteyaboy
1 year ago

How many grams should i use to make solution so that i can do titration?

Cyanide
1 year ago
Cyanide 1 year ago

Yes, do a free cyanide titration with a known amount.  Using distilled water. It should all be free.

biteyaboy
1 year ago

Infact i have NaCN which is not into solution form. How many grams i can for making solution? After that i can do normal titration

Wayne
1 year ago
Wayne 1 year ago
1 like by David

Hi Biteaboy,

Check the information in the site attached, it is very good on what you need to do to successfully analyze cyanide, from sampling to specific titration methods used.  If you study this information you should be able to analyze your NaCN.

http://www.cyanidecode.org/cyanide-facts/sample-analysis

Cheers,

Wayne

biteyaboy
1 year ago

Wayne, I don't know how would i prepare solution of sodium cyanide how many grams should i take into what ml? please help me out with this

kahonde
1 year ago

0.1/100 x (mass of water in grams) x 0.77 should give you 0.1% cyanide.

biteyaboy
1 year ago
biteyaboy 1 year ago

The only problem i am facing now is how to prepare sodium cyanide solution.

I have NaCN in solid form now i want  to turn it into solution. How many grams should i take into how many what volume (mL). Any clarification ob this please

Mikhail
1 year ago
Mikhail 1 year ago
1 like by David

Hi
For example, you can take a powder 0.1 g NaCN + 1 liter of water. After stirring the solution should turn around 0.1 mg / l.
AgNO3 solution titration should be prepared as follows: 1.7331 grams AgNO3 + 1 liter of distilled water.

biteyaboy
1 year ago

Thank you Mikhail for clarification, but silver nitrate should i put first into furnace muffle at 500 degree Celsius for 30 minutes or direct weighing 1.7331 grams?

sorry for many question ; What about indicator i have potassium Iodide which is not yet prepared into solution form. How do you prepare KI to be indicator? same for mass and volume

Mikhail
1 year ago
Mikhail 1 year ago
1 like by David

A solution of AgNO3 cook without roasting.
20 g potassium iodide dissolved in recently boiled and cooled distilled water and bring the volume up to 1 dm3 (liters). Use freshly prepared solution.

biteyaboy
1 year ago
biteyaboy 1 year ago
1 like by David

Thank you very much for details information.

Now i am already get my results NaCN= 257.84ppm and (CN-)  = 136.89 ppm. With these two results i want to know either my cyanide is still good for using or not.

Your input is highly appreciated. 

Mikhail
1 year ago
Mikhail 1 year ago
1 like by Charlie

I will always be happy to help

 

Bhaduri
1 year ago
Bhaduri 1 year ago
1 like by David

Pl. attempt to understand the following mechanism...it should simplify your issue as this is the "old school" determination procedural:

a) Prepare 0.0103M AgNO3...i.e. 0.0103M * (108+14+48) = 1.751-gpL AgNO3; in a clean 100-mL volumetric flask, 1/2 fill w/DDI; weigh out 1.751/10 = 0.1751-g AgNO3 (AR quality that has not been exposed to light) on a 4-figure balance; manually swirl flask to dissolve crystals & make-up to the 100-mL mark w/DDI; cap flask securely & invert several times to homogenize...this is your stock 0.0103M AgNO3 solution for titration;

b) To a clean 100-mL volumetric, 1/2 filled w/DDI, add a caustic (NaOH) pellet (Fisher brand or AR quality), manually swirl to dissolve; accurately weigh 0.1000 g NaCN sample (4-figure balance) & carefully transfer into the caustic solution; swirl & then make up-to volume w/DDI; cap flask securely & invert several times to homogenize...this is your sample NaCN solution for free CN determination;

c) Fill a clean 50-mL burette w/the stock AgNO3; accurately pipette 10-mL NaCN sample solution into a clean100-mL flask; add a couple of drops of rhodanine indicator...the solution should turn yellow (refer to the web or any Chemistry text to prepare rhodanine solution); the end point for the titration is a salmon pink that does not disappear on swirling the flask;

d) AgNO3 + 2NaCN = NaAg(CN)2 + NaNO3

This is a complexation reaction involving 2-moles NaCN for every moles AgNO3; Let's assume you used x-mL AgNO3 for the titration; from the equation, 1000 mL M AgNO3 is equivalent to 2*(23+12+14) g NaCN or x mL 0.0103M AgNO3 is = 0.001009 x g NaCN. This weight of NaCN is present in the 10-mL aliquot used for the titration; so 10-mL contains 0.001009x g NaCN or 1000-mL contains 0.1009x gpL NaCN or 100.9x ppm (by volume) NaCN; Free CN = [(12+14)/(23+12+14)] = 53.06% or 0.5306 * 0.1009x gpL free CN = 0.05354-gpL free CN = 53.54x ppmv free CN;

e) Example: If you used 8.9-mL AgNO3 for the titration, then x = 8.9 mL; so NaCN content of your sample = 100.9 * 8.9 = 898.1 ppmv NaCN; and Free CN content in your sample = 53.54 * 8.9 = 476.5 ppmv. So your sample purity is 89.8% NaCN assuming your analytical instruments/techniques pass muster.

 

biteyaboy
8 months ago

Hi Badhuri, I have questions regarding above explaination
1) Why are we adding Naoh Pellet to NaCN solution? you did mention how many grams should be added ready to prepare the solution? How many gram is required for NaoH?
2) So solution will combine 0.100 g of NaCN and ?? gram of NaCN? Then make up to 1000 ml

ThabisoKwenane
1 year ago
ThabisoKwenane 1 year ago

Good day. Well I don't think NaCN would expire. The procedures stated on how to test the CN- or NaCN are on point. Free cyanide can react to form HCN gas of which there will nolonger be free cyanide present to leach your gold or whichever commodity you will be targeting. I would recommend that you say you want to check your free cyanide rather than checking if whether cyanide has expired. Unless if really it does expire, it would have to be stipulated by the supplier of the period it will be active to be used. Other than that I really don't think that it does expire.


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