Numbers 7:1, 10, 84

On the day Moses set up the Tabernacle, he anointed it and set it apart as holy. He also anointed and set apart all its furnishings and the altar with its utensils.

The leaders also presented dedication gifts for the altar at the time it was anointed. They each placed their gifts before the altar.

So this was the dedication offering brought by the leaders of Israel at the time the altar was anointed: twelve silver platters, twelve silver basins, and twelve gold incense containers.