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What is the best way to get to a higher density?
What happens if sodium polytungstate and tungsten carbide is mixed?
How can I recover Sodium Polytungstate?
What are the advantages of SPT versus lithium metatungstate?
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?
What is the density of Biotite?
Reasons why not to use metal pans?
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?
What are the disadvantages of lithium metatungstate (LMT/LST)?
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.
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.
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.
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.
The density of biotite, a very complex magnesium-iron mica compound, is between 2.8 - 3.2 (varies depending on composition).
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).
Sodium Polytungstate has a pH value of 2-4 (depends on density). At this pH value SPT is stable.
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.
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.
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)
