A new method utilizing phase separation phenomena for the extraction of heavy metal ions used as colorants in colored glass is proposed. Colored soda-lime–silica glass containing Co or Cr as a colorant was remelted with B 2 O 3 to yield soda-lime–borosilicate glass. The soda-lime–borosilicate glass thus obtained was leached in 1M nitric acid at 90°C to dissolve the borate phase. All cations (Na, Ca, Cr and Co) concentrated in the borate phase are successfully leached out with the dissolution of the borate phase, when the amount of the B 2 O 3 added to the glass and heat treatment conditions are properly chosen. Porous silicate glass powders with high SiO 2 purity are obtained as the result of the leaching. Porous glass can also be formed as bulk material by controlling the composition of additives during the remelting.