The invention discloses a method for producing
sodium chromate and co-producing chrome
cast iron by a three-stage process through un-
calcium roasting, aiming at solving the problems of low
roasting efficiency and
high energy consumption in the existing method for producing
chromic salt by un-
calcium roasting. The method for producing
sodium chromate by the three-stage process through un-
calcium roasting comprises the following steps of: A, mixing roasting material in a first stage, mixing
chromite and
sodium carbonate in proportion; B, roasting in the first stage, putting the mixed material in the first stage into a
rotary kiln and performing oxidizing roasting; C, leaching and filtering in the first stage; D, performing second-stage roasting technology; and E, performing third-stage roasting technology. The leaching of clinker after roasting for three times is same as the roasting leaching in the first time and the second time, the
grinding leaching is performed to the clinker by a
wet grinding ball mill, the clinker is filtered by a belt type filter and the filtered
chromium slag by three-stage roasting is obtained by filtering of the belt type filter, the filter liquor is
sodium chromate alkali solution. Compared with the traditional un-calcium roasting technology, the method in the invention adopts the three-stage process un-calcium roasting technology and effectively reduces the mine consumption and the alkali consumption and has the energy-saving and emission-reducing effect.