NOVELTY - Recycling nitrogen gas and sulfur dioxide in calcined pyrite furnace gas by variable frequency-pressure swing adsorption, comprises collecting sulfur dioxide containing furnace gas obtained by calcining of pyrite in fluidized bed furnace, recovering waste heat and purifying, conveying furnace gas into refining furnace and removing entrained dust and rust using air filter, adsorbing in a carbon molecular sieve adsorbent, compressing, adsorbing sulfur dioxide, desorbing and pumping into buffer tank, pressurizing to obtain liquid sulfur dioxide, and collecting nitrogen.    USE - The method is useful for recycling nitrogen gas and sulfur dioxide in calcined pyrite furnace gas by variable frequency-pressure swing adsorption (claimed).    ADVANTAGE - The method achieves comprehensive utilization of calcined pyrite furnace gas and realizes zero discharge, produces high purity liquid sulfur dioxide, and is safe, energy-saving, environmentally friendly and economical.    DETAILED DESCRIPTION - Recycling nitrogen gas and sulfur dioxide in calcined pyrite furnace gas by variable frequency-pressure swing adsorption, comprises (i) collecting sulfur dioxide containing furnace gas obtained by calcining of pyrite in fluidized bed furnace, recovering waste heat by high temperature waste heat recovery boiler, cooling, cyclone dust removing and electric dust removing, purifying under intermediate temperature and low temperature, removing dust and sulfur trioxide, drying and cooling, where the temperature of the furnace gas is 35-40 degrees C, sulfur dioxide content is 7-12%, carbon dioxide and oxygen content is less than 1% and nitrogen content is lea than 87-92%; (ii) conveying furnace gas into polytetrafluoroethylene material lined sulfuric acid refining furnace and removing entrained dust and rust in the furnace gas using air filter; (iii) passing the furnace gas into a tank fitted with carbon molecular sieve as adsorbent and removing small amount of water, oxygen and carbon dioxide, where moisture content is reduced to 2.1-3.2 mg/kg, sulfur dioxide content is reduced to 7.5-12.5% and nitrogen content is reduced to 87.5-92.5%; (iv) introducing furnace gas into a buffer tank, compressing in a frequency conversion compressor, conveying into adsorption column from the bottom of the adsorption column, adsorbing sulfur dioxide in the furnace gas on adsorbent bed layer, separating nitrogen and sulfur dioxide, desorbing sulfur dioxide, pumping into the buffer tank by vacuum pump of frequency converter, pressurizing or freezing to obtain liquid sulfur dioxide, conveying gas-liquid mixture containing liquid sulfur dioxide and gaseous sulfur dioxide into a gas-liquid separator, separating gas-liquid and collecting liquid sulfur dioxide in steel bottle, where the purity is 98.6-99.5%, the adsorbent bed layer is evacuated under vacuum after complete regeneration, the purity of sulfur dioxide obtained from top of the tower is 98.5-99.8%, the pressure is 0.1-0.53 MPa, the nitrogen in the adsorbent bed layer is subjected to reverse adsorption under pressure of 0.1-0.5 MPa and then conveyed into next adsorption circulation process; and (v) compressing or cooling the small amount of non-liquefied sulfur dioxide and then subjecting to gas-liquid separation; and (vi) collecting nitrogen of purity 98.5-99.8% from top of the adsorption tower and then conveyed into the buffer tank.