198 posts
Re: Sulphates of alkali
Dear Mr.Gulam Dastgir,
Theoretically you are correct.The melting point of K2SO4 compound is 1069 deg.cent. and Na2SO4 is 884 deg. cent.To know the form of alkalies present in your clinker,you may do mineralogical analysis your clinker by XRD.Form of alakli sulphate present in your clinker depends on degree of sulphatization or molar ratio and weight % of K2O and Na2O present in your limestone deposit.
I do hope that your query have been clarified.
With kind regards,
R.M.Sahu,
INDIA
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138 posts
Re: Sulphates of alkali
Dear Dastgir,
All Na and K will anyway come out of the kiln in the clinker or in the bypass dusts.
The alkali compounds to be expected in the clinker reflect directly the mass balance of the kiln for alkalies, sulfur and chlorine, and the chemical affinities. This is easily calculated, and to my best knowledge the cycles do not play any role in this.
In the calculations, you first need to perform this mass balance, removing from the inputs, the sulfur lost to the stack as well as any bypass losses. Then you simply combine alkalies with Cl, SO3, and CaO . The "priorities" for the combinations (affinities) are the order in these two lists: {K2O, Na2O} for the alkalies and {Cl, SO3, CaO}.
It maybe paradoxical then that unstable compounds may appear in the clinker. However, there is no other way for these coumpound to exit the kiln. Therefore, the actual volatility reflects the actual kinetics for the decompostions in the kiln. If 20% of a species is "trapped" in the hot meal and cannot decompose or volatilise, then the cycles will build up. In this case, the hot meal enrichment will be 5, and in this way 100% of the compound will finally leave the kiln.
Thermodynamics alone could not explain why 20% would trapped in this example, and it may well be related to granulometry, mineralogy, temperatures, gas compositions, speed of the kiln ...
Note however, that the stack losses will depend also on the stabilities of the sulfates and the "captation" of in the upper stages.
As you may be interrested, below is the decomposition pressure of some alkali compounds.
72 posts
Re: Sulphates of alkali
Dear lalbatros;
Do you know that you are the first one attaching something in this forum, i tried alot but i failed i don't know why! could you please tell me how can i attach image to this forum? I believe images, graphics, and tables may explain alot of point more than words
138 posts
Re: Sulphates of alkali
In "Image URL", you need to tell where your picture is located.
Your image must be stored somewhere on the web.
Cemnet doesn't offer you any storage to upload your pictures.
Therefore, you need to upload your pictures somewhere else.
I use a free yahoo accpunt for that.
There are many other free ways to upload pictures and files to the web.