Pyrometallurgy: Roasting, Smelting, Refining & Electrowinning

Pyrometallurgy: Roasting, Smelting, Refining & Electrowinning2017-04-21T02:33:06-04:00
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Started by JohnnyD
Muriatic Acid + Clorox Bleach is dissolving my gold, but Sodium Metabisulfate (stump out) is not dropping the gold back out in pure form it's only changing colors of my solution. no precipitation.
Last replied to by Saxe
Even though these posts I am commenting on today are 3 years old, people still read and rely on them. All of the comments related to Johnny D's question concerning inconsistent results are good - but...
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2017
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Started by Marshal Meru
I would like to start a new discussion on the treatment of E-waste. The production/consumption of EEEs is ever increasing with the concurrent decrease in their lifespan. How do you see the current status and future of treatment/recovery/recycling of ...
Last replied to by Moonglow
Can anyone recommend a good and reliable CPU scrap supplier?
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Started by Subhash-Kumar-Roy
Are there in general set point minimums of calcium percentage that can't affect gold stripping efficiency? Hence don't need to do acid wash.
Last commented on by Walter silas
Hi could you perphaps have a literature back up of a minimum calcium % on the carbon. i mean a literature that suggests a 1%is fine
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958
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Started by
Hi my zinc sulphate manufacturing process, I am having Zinc dross containing 4% Iron. To make pure Zinc sulphate solution we have to remove Iron. Is there any solvent available to separate Iron from Zinc?
Last replied to by K@TTU
If high Zinc concentration Streams having Zn 45-50 g/l  using SX with D2PHA is economically suitable process with neutralization with caustic . In our process stream has contain high Mg and Mn levels...
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Started by
Disposal of Spent Activated Carbon: How can I safely dispose spent carbon which has long been used in the elution process and how can I verify if the carbon contains any residual gold?
Last replied to by James Nkali
hi,need help please, i have more than 30 tonnes of eluted activated carbon with 50ppm of Gold and 90 ppm of copper,    i dont want to use Elution machine because its more expensive, am looking forw...
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Started by Sachin Prakash
How to avoid abnormal long elution period from a zadra elution circuit, is this cyanide depletion, eluant composition, flow of eluant to electrowinning cells or temperature?
Last commented on by Max V
Where can I buy a Pressurizer zara Stripping
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825
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Started by Paul Morrow
I am looking for this extractant (for the recovery of gallium from sulphuric acid), does anyone know a supplier?I contacted several suppliers, Exxon Mobil Chemicals, Cytec, Daihachi and Solvay-Rhodia, but none seems to have this product in their port...
Last replied to by David
Try chemnet.com at http://bit.ly/1MFi7kW?
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2111
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Started by Bob Mathias
Please advice how can I increase the gold purity during smelting from sulphide ore, fluxes used are Borax (dehydrated), Silica, Soda ash and Potassium Nitrate. It is for smelting of EW sludge and I want to reduce the amount of silver and base metal t...
Last commented on by vijay
nice advice
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639
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Started by Sachin Prakash
What can cause weight discrepancy in a Dore bar (Gold alloy) between the initial value (after refining and quenching) and the value after shipping from 312 m elevation to 218 m elevation.Discrepancy is about 3.5 g out of 24 kg. Sources considered:Gr...
Last replied to by Oberfuhrer
This difference is caused by encrusted water in small pores, look at the appearance of the bars Dore, and if these have too many pores, you must first remove the water with a compressor will come out ...
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711
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Started by Raje Singh
What is a good coagulant for carbon fines? What is the best way to measure the temperature of a molten Dore bar in a furnace? Good software for determining angularity/roundness of carbon?Currently, we have a de-watering screen "for the stripped carbo...
Last replied to by
Suggest you try removing water faster such as a plate and frame press or vacuum rather than putting too much cost into flocculants and other devices. OK you will need to do some testing to find the ri...
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586
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Started by Sachin Prakash
What options are there for the chemical refining silver bars with 2-5 % gold?
Last replied to by Sachin Prakash
Small volume for example:The precipitated from Merrill Crowe has this values in 75 kg : 0.5% Au, 22% Ag, 20% Pb and 57% Zn after the first foundry the new values in 15 kg are 2% Au, 88% Ag, the rest P...
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Started by Raje Singh
Is there any suitable oxidizing agent for conversion of copper nitrate into copper oxide which will be useful in separation of copper from silver nitrate electrolyte in HSSR process?
Last replied to by Unterstarm
I agree; you can see a detailed explanation in United States patent US 8,282,903 B2
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Started by Sachin Prakash
We prepare our gold concentrate, which contains about 8ppm Ag, for smelt through treatment with nitric acid? This silver is not seen in the final bullion because I suppose it is dissolved in the nitric acid as silver nitrate. I want to recover this s...
Last replied to by
Addition of the Chloride has to be such that the [Cl-] is kept in exact stoichiometric balance to the silver molarity, too little silver nitrate will remain room much and soluble silver di Chl...
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Started by Rahil Khan
What might be the some of the possible causes of high Au on Barren Carbon after elution (AARL), when all your temperatures, pressures and flow rates are good!
Last replied to by Standartenfurer
Poor acid washing resulting in inorganic fouling can definitely increase your barren grades. At a previous mine we had many problems with acid washing such that we were not acid washing for almost one...
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Started by
How I can prevent oxidation in the anodes in electro-winning cell to get gold in cathodes?
Last replied to by Obergruppenfuhrer
In addition to the previous points (low caustic, high chloride levels, and high current density) you will get corrosion if your flow rate through the cell is too low. Typical safe flows are about 7m3...
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Started by Tarun Karakoti
I need some data for approximate carbon losses as fines after regeneration of carbon (every cycle) and after new carbon attrition.
Last replied to by Oberstorm
The manufacturer considers normal to lose up to 4% of carbon after each cycle. In the regeneration process are the main attrition.
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Started by
When testing for Au concentrations using Lead Collection Fire Assay Methods; what valuable information is lost when only conducting Fire Assays?
Last replied to by Hauptsturm
Concentration and temperature are two fundamental kinetic drivers in any chemical reaction. Could it be that as you increase cyanide concentration you overcome the activation energy required for chemi...
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458
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Started by Amar
How can we separate out Pb, Cu, Sb impurities from BiCl3 solution? Ultimate target is to produce salable Bi-compound.
Last replied to by OberstGruppen
Chlorination roasting should solve part of your problem instead of acid leaching. BiCl3 fumes at low temperature.
9
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689
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Started by Tarun Karakoti
Fire assays are returning double the Au reading when using a standard aqua regia method. Suggestions are that the preg robbing material could be adsorbing the gold during the acid digest, which would not be transferred to the aqueous phase to organic...
Last replied to by
It is a possibility, pay close attention to your ashing temperature and time. Higher and longer are not necessarily better.
9
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1217
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Started by Paul Morrow
I have question about Electrowinning with (NaCn Solution and H2o2) what is the best Amperage to get maximum result? How to test if there is no more gold in the solution?
Last replied to by Sudhirkumar
Sorry did not see earlier comments about the absence of AAS/FA; suggest you access Vogel's text on Qualitative Analyses there are a number of easy colorimetric techniques to define the presence of sol...
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634
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Started by Hauptsturm
What do you think about controlling the electric current through the dosage of sodium hydroxide?We have problems with control the electric current in the electrowinning. The actual concentration is 1,5% (NaOH), the pH is 11,0 to 11,8 in the solution....
Last replied to by Obergruppenfuhrer
Caustic levels below 0.75% will cost you electrowinning efficiency. Many operations run as high as 2% caustic. It is important to determine the caustic level by titration and not just control by pH. I...
1
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1101
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Started by jeremy_911met
Hi, my name is jeremy and a geologist, hence the simple questionWhat is the minimum feed size fraction for tin smelting. In other words, at what feed size causes the Cassiterite ore to vaporise and you lose the tin?
Last replied to by David
Hi Jeremy,I do not think size matters much. Maybe 100 mesh. See the PDF here at movie.https://www.youtube.com/watch?v=IKqTCvMEodA
14
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542
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Started by Subhash-Kumar-Roy
We produce gold and silver bar with Merrill Crowe process. The bar has some lead but we remove this metal with oxy-blower in the refinery. I want to learn, have a different process or idea?
Last replied to by Hauptsturm
Lead is in PLS is unusual as Pb(CN)2 is insoluble, nevertheless you’re not the first in my limited experience.Again the metallurgist has several options; one is to removal prior to the MC Zinc cemen...
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Started by Paul Morrow
We used to analyse Gold by fire assay finished by AAS or gravimetric but as you know the cost in such techniques is very high and the selection of flux may leads to errors specially in low grade (0,2ppm) analysis in my project I’m working on someth...
Last replied to by Paul Morrow
I will contact you but the procedures are they using AA or? Do you understand that the aim is to do it by electrochemical method using one the electrode mentioned earlier, and understand what's beyond...
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1573
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Started by Zander Barcalow
What’s the difference between organic continuous and aqueous continuous mixing in solvent extraction? And which of them is better?
Last replied to by
Excellent description. I have had very little to do with SX so this was an interesting read. I particularly liked the beer analogy - giving a real world 'visual' example that a lay person can identify...
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601
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Started by
Does anyone know of SX applications in the plating industry? I doubt if it can be used directly on production baths because contamination by organic compounds adversely affects plating.
Last replied to by
The MECER process recycles 95 % of the etch liquor back to the etching machine. However, I agree that most applications are treating plating solutions without recycle.
4
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565
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Started by
How do you improve the plant mixer efficiency both in organic and aqueous phase apart from flows, turbine speed? Lab test is more of batch than continuous process and equilibrium is reached/assumed.
Last replied to by Maya Rothman
I think everyone has given you a good direction. I suggest you also make sure that you are mixing the phases at A/O close to 1 and that you have a residence time of 2-3 minutes in each mixer tank base...
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1173
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Started by
I would like to have experts’ suggestion about an application of SX in small scale copper elector-refinery (3-5 Kt/Y) and if it is tangible, are there any successful references. Main concept is to refine 97-98% grade copper Anodes to 99.999 pur...
Last replied to by
In my opinion there is option of combining electro refining circuit (large) with a small SX-EW as releasing impurities. Everything depends on the level of impurities.I like to solve the technical prob...
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Started by Victor Bergman
The use of microwaves for carbon activation was invented in the 1980's and it earned my privilege to study metallurgy. The issue is that it is cost prohibitive and the name MICRO exactly spells out the problem.It worked fantastic in small laboratory ...
Last replied to by
I looked at that for floating activated carbon fines (for regeneration) out of filter-cake, without much success. The concept was that activated carbon would absorb the MW energy preferentially over o...
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862
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Started by
I need to know what chemical reaction takes place when pyrrhotite is heated in presence of air. It is evident that Fe3O4 and SO2 will be produced but unable to figure out the exact equation.
Last replied to by
Fe (1-x) S as fine powder could react with SO2 gas over 150 centigrade in aerated environment at 0.6 atm. Try on dryer plate
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Started by Jean Rasczak
In Sizing a CoSO4 mixing system for a Cu EW plant. This system must be sufficiently robust to source CoSO4 from different suppliers so anhydrous to heptahydrate products and up to very coarse particle size
Last replied to by Zander Barcalow
http://www.trentu.ca/chemistry/chem321h/labmanual.pdfhttps://www.ec.gc.ca/ese-ees/8E18277B-457E-4073-8F27-EF5878648820/batch10_4substances(1)_en.pdf
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Started by mine master
Hi, everybodyI want to separate an alloy of gold and silver with gold content between 25% and 92% Au.As you know, in the alloy of gold and silver with gold content of less than 25%, Ag can be dissolved with sulfuric Acid or Nitric Acid.In the alloy o...
Last replied to by David
The Miller process consists of injecting chlorine into the charge through a clay tube connected to silver tubing that is connected to the chlorine source. About 0.2 kg (0.5 Ib) of borax glass is sp...
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Started by Zander Barcalow
I am doing a project and I need to quantify the change in reaction rate of iron reduction to the change in surface area of iron ore lump. What is the effect and impact of surface area of iron ore lumps on the kinetics of blast furnace? Is there any m...
Last replied to by
Have you looked at any of the shrinking core models? There's different equations based on the rate controlling steps: diffusion, ash layer and chemically rate control. You might find this article usef...
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Started by David
Here are a few PDFs on Electronic Scrap Recycling I found for you.http://911Metallurgist.com/C/ElectronicScrapRecycling/Refining-Precious-Metal-Wastes-C-M-Hoke.pdfhttp://911Metallurgist.com/C/ElectronicScrapRecycling/Metal-Recovery.pdfhttp://911Meta...
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Started by Maya Rothman
I need to know the correct dosage addition of zinc (Kg Zn / ppm Ag) to have a better precipitation of silver?
Last replied to by Helena Russell
Please, do not forget mercury , because is another element that precipitates with zinc addition.Another issue , higher grade Au and Ag lower ratio Zn / (Au + Ag). Keep in mind Pourbaix's diagram and t...

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