The　evolution　of　silica　during　the　lime-free　roasting　and　their　roles　were　investigated　using　chromium-containing　slag　with　high　content　of　ferric　oxide　and　silica.　The　siliceous　salt　phases　were　analyzed　by　means　of　X-ray　diffraction,　scanning　electron　microscope,　and　energy-dispersive　X-ray　spectroscopy.　The　reaction　rule　involved　with　silicon-containing　compounds　in　the　roasting　process　was　also　discussed.　The　results　showed　that　both　oxidation　of　Cr2O3　and　leaching　of　Na2CrO4　were　influenced　by　the　siliceous　salts.　It　suggested　that　roasting　temperature　and　the　amount　of　alkali　act　as　important　factors　for　the　phase　transformation　of　silicon.　NaFe(SiO3)2　was　formed　in　the　temperature　which　is　best　for　the　production　of　Na2CrO4,　while　excess　amount　of　alkali　could　decompose　acmite　into　NaFeO2　and　Na2SiO3.　It　was　observed　that　a　large　amount　of　insoluble　NaFe(SiO3)2　took　shape　during　the　lime-free　roasting　when　the　temperature　was　above　1273　K　(1000 °C).　The　extracting　rate　of　chromium　from　chromium-containing　slag　roasted　at　1373　K　(1100 °C)　was　only　29.99　pct　and　almost　no　silicon　was　leached　out.　©　2015,　The　Minerals,　Metals　&　Materials　Society　and　ASM　International.