The invention belongs to the technical field of 
environmental protection, and relates to the recycling of 
chromium-rich 
sludge, in particular to a method for producing 
chromium sesquioxide through 
chromium-rich 
sludge. The method comprises the following effective steps: a, firstly, washing and 
drying chromium-containing 
sludge; b, then, evenly 
grinding the dried chromium-containing sludge, transferring the chromium-containing sludge into a calcining 
kiln to directly heat the chromium-containing sludge, increasing the temperature of the chromium-containing sludge to 530 to 570 DEG C within 1.5to 2 hours, and then maintaining the temperature for 1 to 1.5 hours; c, transferring the chromium-containing sludge into a cooling 
kiln after heating is accomplished, reducing the temperature of the chromium-containing sludge to 60 to 90 DEG C, adding 
hydrochloric acid and water at the end of cooling, and uniformly stirring; d, transferring the uniformly stirred chromium-containing sludge into a 
filter press to perform filter pressing on the chromium-containing sludge, and washing filter residue to be neutral; e, adding water and 
hydrofluoric acid to the washed filter residue, stirring for 0.5hour, then transferring the filter residue into a 
filter press to perform filter pressing on the filter residue, and washing the filter residue to be neutral; f, then transferring the filter residueinto a high-temperature calcining 
kiln, performing burning and heating on the filter residue through 
coal gas, increasing the temperature of the filter residue to 1320 to 1400 within 2 hours, maintaining the temperature for 50 to 80 minutes, and then transferring the filter residue into the cooling kiln to reduce the temperature of the filter residue to below 40 DEG C, so as to obtain a finished product namely the 
chromium sesquioxide.