Trial by fire: Safely heating sand without it agglomerating? Wikipidia quotes a melting point of 1713C for sand.
I went on the beach to get some sand. I assume it's a mix of all kinds of stuff.
The finality is to prepare a big pile of clean sand to use as filtering aid above paper filter (among other uses).
I'd like to get rid of plastics &amp; organics by heating it up.
What temperature can I bring it up to before the smallest particles start to agglomerate? What temperature would you recommend for pyrolysing as much of everything in there that is not SiO2 such that it either degrades or later more easily disssolves in water?
Sand is not available as a reagent grade chemical, but rather is mineral origin particles of a size between 0.074 and 4.75 millimeters. Gravel is bigger, silt is smaller.
Pure silica (SiO$_2$) may melt at 1713$^o$, but the melting point of real sand is given as 1500 to 1610, and you can probably find some numbers outside that range.
Perhaps more of an issue than the exact melting point is how much are you preparing to treat? And with what heat source? And what sort of vessel are you going to contain the sand in while you heat it up and cool it down? And for what purpose?
Thin layers of sand (small overall quantity) may burn off organics relatively easily, say in a stainless steel measuring cup, with a propane torch  - although, the handle will get hot, so arrange some sort of apparatus to hold the vessel.
Different materials will need different temperatures and times to burn off completely; perhaps you can heat till smoke stops coming off and the sand looks like it is a bright red or orange color. I doubt that you would have to get to a yellow.