‘ And they burnt the city with fire, and all that was in it, only the silver and the gold, and the vessels of brass and iron, they put into the treasury of the house of YHWH.'
This was a purifying ritual, devoting all to YHWH. Even the latter were probably burned for purification before being put into the treasury (Numbers 31:22-23).
“The house of YHWH.” Compare Judges 19:18; Judges 20:18; Genesis 28:17; 1 Samuel 1:7; Exodus 23:19; Exodus 34:26. The ‘house of YHWH' was the place where He was to be approached, in this case the Tabernacle. As Genesis 28:17 makes absolutely clear ‘house' here does not necessarily signify a building.