A suspension roasting method for industrial processing of iron and manganese ores for a suspension roasting system for industrial processing of iron and manganese ores, the system comprising a feeding bin, a screw feeder, a Venturi dryer, a first cyclone preheater, a second cyclone preheater, a pre-oxidation suspension roasting furnace, a thermal separation cyclone cylinder, a first flow sealing valve, a suspension and reduction roasting furnace, a second flow sealing valve, a first cooling cyclone cylinder, a second cooling cyclone cylinder, a third cooling cyclone cylinder, a collecting bin, a grinding machine, a magnetic ore separator, a dust collector, a draught fan, a coal gas source and a nitrogen gas source;
- wherein an outlet of the feeding bin is opposite to a feeding end of the screw feeder, and a discharging end of the screw feeder is opposite to a feed opening of the Venturi dryer;
- wherein a discharge opening of the Venturi dryer communicates with a feed opening of the first cyclone preheater, a discharge opening of the first cyclone preheater communicates with a feed opening of the second cyclone preheater, a discharge opening of the second cyclone preheater communicates with a feed opening in a lower part of the pre-oxidation suspension roasting furnace, and a burner and an air inlet are arranged in a bottom part of the pre-oxidation suspension roasting furnace;
- wherein an upper part of the pre-oxidation suspension roasting furnace communicates with a first feed opening of the thermal separation cyclone cylinder through a first pipeline, a discharge opening of the thermal separation cyclone cylinder communicates with an inlet of the first flow sealing valve, an outlet of the first flow sealing valve communicates with a first feed opening in a top part of the suspension and reduction roasting furnace, and a plurality of air inlets are formed in a bottom part of the suspension and reduction roasting furnace and simultaneously communicate with the coal gas source and the nitrogen gas source;
- wherein a discharge opening in a side part of the suspension and reduction roasting furnace communicates with an inlet of the second flow sealing valve, an outlet of the second flow sealing valve communicates with a feed opening of the first cooling cyclone cylinder, a discharge opening of the first cooling cyclone cylinder communicates with a feed opening of the second cooling cyclone cylinder, a discharge opening of the second cooling cyclone cylinder communicates with a feed opening of the third cooling cyclone cylinder, and a discharge opening of the third cooling cyclone cylinder communicates with an inlet of the collecting bin;
- wherein an outlet of the collecting bin cooperates with an inlet of the grinding machine, and an outlet of the grinding machine cooperates with a feed opening of the magnetic ore separator;
- wherein an air outlet of the first cyclone preheater communicates with an air inlet of the dust collector, and an air outlet of the dust collector communicates with the draught fan;
- wherein an air outlet of the third cooling cyclone cylinder communicates with the feed opening of the second cooling cyclone cylinder, an air outlet of the second cooling cyclone cylinder communicates with the feed opening of the first cooling cyclone cylinder, an air outlet of the first cooling cyclone cylinder communicates with the air inlet in the bottom part of the pre-oxidation suspension roasting furnace, and an air inlet of the third cooling cyclone cylinder is provided with an air pipeline for inflation of air;
- the method comprising the following steps:
- (1) crushing iron and manganese ores until a total mass of a part with a grain size of 1 mm being greater than or equal to 80% to obtain dust ores, wherein an iron grade TFe of the iron and manganese ores is 30-55%, and a manganese grade TMn of the iron and manganese ores is 10-30%;
- (2) placing the dust ores in the feeding bin, then conveying the dust ores into the screw feeder, and continuously feeding the dust ores into the Venturi dryer through the screw feeder;
- (3) starting the draught fan and generating negative pressure by the dust collector, the first cyclone preheater, the second cyclone preheater, the Venturi dryer, the thermal separation cyclone cylinder and the pre-oxidation suspension roasting furnace, introducing combustion gas into the Venturi dryer, mixing the combustion gas with the dust ores, and removing adsorbing water of the dust ores;
- controlling a material temperature of the discharge opening of the Venturi dryer to be 150-180° C.;
- (4) introducing the combustion gas and the dust ores without the adsorbing water to enter the first cyclone preheater from the Venturi dryer, introducing solid materials after cyclonic separation to the second cyclone preheater, preheating the solid materials after cyclonic separation for the second time in the second cyclone preheater to 400-700° C., and then introducing the preheated solid materials to the pre-oxidation suspension roasting furnace;
- (5) starting the burner to burn introduced coal gas to generate high-temperature gas to enter the pre-oxidation suspension roasting furnace, while introducing air into the pre-oxidation suspension roasting furnace through the air inlet in the bottom part of the pre-oxidation suspension roasting furnace, under an action of air flow and negative pressure, so that the solid materials in the pre-oxidation suspension roasting furnace is in a suspension state, heating the solid materials to 550-900° C. for roasting, so that carbonate minerals in the solid materials is subjected to thermal decomposition, and manganese minerals and iron minerals is subjected to an oxidizing reaction;
- discharging all roasted solid materials from the upper part of the pre-oxidation suspension roasting furnace along with the air flow through the first pipeline to introduce the solid materials to the thermal separation cyclone cylinder;
- using the solid materials after cyclonic separation as oxidizing slag powder including Fe2O3 and Mn2O3, discharging the solid materials from the thermal separation cyclone cylinder, and introducing the discharged solid materials the suspension and reduction roasting furnace through the first flow sealing valve;
- (6) introducing the coal gas and nitrogen gas from the air inlets in the bottom part of the suspension and reduction roasting furnace, so that the oxidizing slag powder is in a suspension state under an action of the air flow and the negative pressure, performing reducing roasting at 500-650° C., performing reduction on weakly magnetic Fe2O3 to generate strongly magnetic Fe3O4, and performing reduction on Mn2O3 to generate MnO;
- using the solid materials after reducing roasting as reducing slag powder, and discharging the reducing slag powder from the side part of the suspension and reduction roasting furnace;
- (7) sequentially passing the reducing slag powder discharged from the suspension and reduction roasting furnace through the first cooling cyclone cylinder, the second cooling cyclone cylinder and the third cooling cyclone cylinder after entering the second flow sealing valve, performing cooling the reducing slag powder in a temperature less than or equal to 200° C., introducing the cooled reducing slag powder to the collecting bin, introducing the gas separated by the third cooling cyclone cylinder in a cyclonic separation process into the feed opening of the second cooling cyclone cylinder, introducing the gas separated by the second cooling cyclone cylinder in a cyclonic separation process into the feed opening of the first cooling cyclone cylinder, and introducing the gas separated by the first cooling cyclone cylinder in a cyclonic separation process into the air inlet in the bottom part of the pre-oxidation suspension roasting furnace, while introducing air through an air inlet of the third cooling cyclone cylinder;
- and
- (8) conveying the reducing slag powder in the collecting bin to the grinding machine, performing grinding until a part with a grain size of 0.074 mm accounts for 75-85% of a total mass, introducing the ground powder to the magnetic ore separator for magnetic ore separation, and using magnetic products obtained by magnetic ore separation as iron ore concentrates and nonmagnetic products obtained by magnetic ore separation as manganese ore concentrates.