The process of strongly heating a concentrated ore in the absence of air to a temperature that is not sufficient to melt the ore is called ____ .

Explanation

**Step-by-Step Solution:**

1. **Understanding the Process**: The question refers to a specific process involving concentrated ore. Concentrated ore is the result of extracting metals from their ores, and it contains a higher percentage of the desired metal.

2. **Heating in Absence of Air**: The process involves heating the concentrated ore without the presence of air. This is important because the absence of air prevents oxidation and other reactions that could alter the composition of the ore.

3. **Temperature Consideration**: The key detail in the question is that the temperature used for heating is not high enough to melt the ore. This means that the process is focused on removing impurities rather than converting the ore into a liquid state.

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