[eric2011 (OP)]

Hi

Refer to the question above. When those chemicals are mixed together and heated in a furnce lets say at 1600C what happens as a result?

And what happens also when  you add silica on the mix and heat at that temperature?

[alancalverd]

1.Slag

2. Glassy slag.

Just guessing.

[paul cotter]

Manganese dioxide will not exist at 1600c. It will lose oxygen and turn into a lower oxide, offhand I can't remember.

[Bored chemist]

I'm fairly sure that the reaction of MnO2 with Al is so exothermic that you vaporise the Mn produced.
Adding sand might soak up some of the heat and reduce the temperature .

Also, as has been pointed out, the hot MnO2 will decompose to give oxygen which will splatter stuff around.

[alancalverd]

But the OP stated aluminum oxide, so no thermite reaction, just a lump of oxide slag.

[eric2011 (OP)]

I was talking abouit mangansese dioxide and aaluminuim oxide. I read somehere that aluiminum oxide melting point can be reduced to 1520 C hen mixed with mangannese oxide which has a melting point of 1945 C. My curiousity now is becaiuse Manganese dioxide has a melting point of just 500 C, how much temperature will  it be able to  reduce aluminum oxide melting point to when mixed  because it has a lower melting point than manganese oxide?

[Bored chemist]

But the OP stated aluminum oxide, so no thermite reaction, just a lump of oxide slag.

Oop!
I missed that.
I'm pretty sure that , by the time you get to 1600C the MnO2 will have decomposed to MnO
If you get the proportions right, and the mixture hot enough,you might be able to make a manganese spinel.
It might be a pretty colour.

[eric2011 (OP)]

Let me ask also this, if manganese oxide melting point is 1945 C what other oxides or carbonates can reduce its melting point if mixed and heated?

[Bored chemist]

Adding essentially any impurity to anything will reduce the melting point.
Trying to calculate in advance how much  they will reduce it is difficult. (except in the case of very small amounts where the nature of the impurity doesn't matter much).

The only practical way to find out is by experiment.
If you are lucky, people publish the results of the experiments.

https://www.researchgate.net/figure/The-phase-diagram-of-the-MnO-Al-2-O-3-system_fig2_222902521

[eric2011 (OP)]

When you heat Mno2 decomposes to Mno. What about Mn2O3 which is manganese 3 oxide. And it has a low melting point. So if I mix aluminum oxide + mn2O3 will it loeer aluminum oxide melting point to a lower temperature range because Mn2O3 has a melting point of 808 C

Guys be patient with I am still learning chemistry

[paul cotter]

There is also mn3o4. At what temperatures one oxidation state changes to another, I don't know. You would need a comprehensive treatise on manganese chemistry, which is quite complex. The forum "sciencemadness" has a library which, from memory, would have the info. Look for a detailed work on inorganic chemistry.