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I believe it's termed "injecting" not "pumping" but yes, it's certainly possible.
Coal fired electric power plants grind the coal to a very fine dust and then blow the dust into the central burner.
This particular article is a summary of some DOE research for a Blast Furnace Granulated Coal Injection System Demonstration Project.
And this article discusses some of the hazards from a National Fire Protection Association perspective. Coal dust having the particular dangerous property of being explosive and all that...
As far as specifics regarding danger, I suspect it will vary depending upon the material(s) involved in the powder.
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