Is it safe to heat fluorite (CaF2) to 140 °C?
The melting point of $\ce{CaF2}$ is over $\pu{1400°C}$. There is no way $\ce{F2}$ can be generated without electrolysis of the molten $\ce{CaF2}$. $\ce{HF}$ is produced by reaction of conc sulfuric acid on $\ce{CaF2}$. Concentrated $\ce{HCl}$ does react with fluorite to some extend, but the reaction is very slow so, unless your operators drool like the monster from Alien, there is no chance of $\ce{HF}$ formation.