 |
 |
 |
 |
 |
 |
 |
 |
 |
What is the best way to get to a higher density?
What happens if sodium polytungstate and tungsten carbide is mixed?
Why should I remove calcium ions from my material?
How can I recover Sodium Polytungstate?
What are the advantages of SPT versus lithium metatungstate?
Can I use metal pans to handle sodium polytungstate?
Could electrons cause a precipitation?
Can Hornblende cause discolorations?
What is the tungsten trioxide (WO3) amount in sodium polytungstate?
Will organic compounds effect the separation process?
How will Iron Sulfide effect the sodium polytungstate solution?
How can the SPT be re-purified?
How does SPT react with organic?
What is the right temperature for SPT in a drying oven?
What is the density of Biotite?
How can I avoid the precipitation with calcium ions?
Reasons why not to use metal pans?
Can I use afloat sink separation for calcium carbonate?
What is the pH value of sodium polytungstate?
Can I boil the SPT solution under vacuum condition?
What is the viscosity of SPT versa lithium?
Why does SPT crystalizes at high densities?
At higher densities the viscosity increases. What can I do?
I was wondering what the organic carbon content was of the SPT?
What are the disadvantages of lithium metatungstate (LMT/LST)?
What is the minimum amount required for performing sink and float tests in a mineral Zn/Pb ore?
Can I use something other than water with sodium polytungstate?
It is best to add solid in order to obtain a higher concentration.
Tungsten Carbide (TC) will not dissolve in the sodium polytungstate (SPT) solution. It will make a two phase slurry with liquid and particles of carbide. The smaller the carbide particles are the better your results will be. Please note: Since Tungsten Carbide is a black powder (with a grain size of less then 0.8 µm) the suspension of Tungsten Carbide and SPT is dark and opaque.
It is very important to remove all calcium ions from any liquid or material added to the SPT solution, because the calcium ions will turn the solution blue
Concerning removal of yellow-brown color from solution by addition of activated charcoal the rule is: The simpler the component, the more difficult it is. The fastest and simplest way to determine is by trail and error, i.e. Make a simple experiment.
The polytungstate solution can be recovered by washing respective particles with distilled or demineralized water and then evaporating to the density required respectively solid polytungstate is added.
(You mentioned something with Carbon isotopes). The extraction does not alter the isotope ratio. If “contamination”is detrimental the sample removed from one solution should be washed before introducing the same into the next solution.
There are several advantages of sodium polytungstate over lithium metatungstate, Although, both are non-toxic, sodium polytungstate's density is easily adjustable - simply add more water to lower the density or add additional SPT powder to get back to a higher density. The density of a lithium solution can be lowered by adding water, but increasing the same solution involves a time consuming evaporation process.
After all Lithium Metatungstate contains 110 grams of Sodium Polytungstate! The analysis was done by The Akademy of science, Adlershof Germany.
At this temperature decomposition is very likely.
No you should not use metal pans. Use only 100% stainless steel pans otherwise do not use it. Metal pans if not 100% stainless steel might contain compounds that act as reducing agents. Do not take any chance.
Weather or not the 100% stainless steel metal pans pull out electrons we don’t know but SPT seems to be neutral in regards to electrons.
Hornblende as such does not cause discoloration. Impurities in the Hornblende can, if they are of a reducing character. Thus samples have to be thoroughly washed before getting into contact with SPT. Note: Hornblende are very complex minerals, which contains: aluminum, silica, titanium, iron (ferro), magnesia, calcium, potassium (kalium) and sodium (natrium).
The tungsten trioxide (WO3) amount in sodium polytungstate is between 86% to 87%.
It depends on the type and amount. The simplest way is to experiment with small amounts in a test tube.
Iron sulfide (FeS) is a reducing agent. Reducing agents should be avoided by all means, since they may turn the solution into a bluish coloration. A small addition approximate 30% of hydrogen peroxide (H2O2) solution may be required to restore the original color.
Once dry, rinsing it simply causing it to go back into solution. How is that avoided? Suggestion: Use a suitable extraction agent for the impurities.
SPT does not react with chemically inactive organic compounds like carbon, graphite etc. However, strangle basic organic will destroy the compound and turn the solution blue (see also reducing agents).
A temperature of about 248°F (120°C) is fine. Lowest at around 212°F (100°C) and highest at 284°F (140°C) depending on the concentration. Note: Minerals and all solids should be removed before evaporation. (See recovery information).
The density of biotite, a very complex magnesium-iron mica compound, is between 2.8 - 3.2 (varies depending on composition).
As to the precipitate formed with calcium ions this can be avoided by chelating these ions under using ethylenediamine tetraacetic acid C-N(CH2COOH)2 used in the household to render tap water soft. Please test first small samples,
Because any metal might contain compounds that act as reducing agents. Zinc, iron, aluminum and copper are examples of metals which reacts with sodium polytungstate solutions. Use only 100% stainless steel equipment, glass or plastic containers otherwise do not use it. (see reducing agent).
If calcium carbonate in the form of aragonite (d=2.93) or calcite (d= 2.71) differs sufficiently from the density of the silicate minerals under consideration, a float-sink separation poses no problem. But note that soluble calcium ions will form a precipitate. Otherwise there is no chemical interaction.
Sodium Polytungstate aka sodium metatungstate contains no carbon or carbon compounds whatsoever.
Sodium Polytungstate has always the same pH value of 2-3. Irrespective of its origin (different manufacturers) SPT always has the same pH value. The pH range for sodium polytungstate is stable between 2-14. (See pH value).
Boiling a diluted solution for concentration purposes is very time consuming process. Doing it under vacuum conditions does not help much. It is best to add solid in order to obtain a higher concentration. See in particular the graph of the leaflet which gives you any desired concentration on the basis of water versus amount of solid.
The viscosity of sodium polytungstate versa lithium metatungstate at higher densities is only slightly higher. To achieve a rapid and quantitative separation you can centrifuge the mixture instead of the sink-float procedure, thus easily overcoming viscosity problems.
The solution is probably over saturated. In view of the high density of the liquid floating crystals are not unusual. SPT will actually only crystalize from oversaturated solutions. The higher the temperature, the more solid SPT will dissolve. You may remove the crystales on top of your beaker and continue to work.
Filter the milky solution and try to make up with distilled water.
With short centrifuging you can decrease the viscosity immediatley. To achieve a rapid and quantitative separation you can centrifuge the mixture instead of the sink float procedure, thus easily overcoming viscosity problems.
SPT contains traces of carbon. C < 40 ppm
We needed a density of 2.85. It is very difficult to adjust the separating agent LST to the required density of 2.85. Only after we heating LST to about 30ºC, then it is possible to work for a few hours satisfactorily.
(Prof. Dr. W. Buggisch, University of Erlangen - Germany)
The minimum amount naturally depends on the amount of solids to be separated. For a sample ore of 75g to 125g a solution of 500 ml at the desired density of 2.8 g/ml will be enough. Please note that 3kg of SPT at a density of 2.8 g/ml will make 650 ml solution.
You can use Methanol (CH3OH) instead of destilled water.
