Gaseous suspension roasting device and method for high-phosphorus oolitic iron ore

Abstract

The invention discloses a high-phosphorus oolitic iron ore gaseous suspension roasting device and method, and belongs to the technical field of mineral processing suspension roasting, and the device comprises a feeding system, an oxidizing roasting system, an oxidized roasted product cooling system, a reduction system, a reduced roasted product cooling system and a dust removal and ash return system. High-phosphorus oolitic iron ore with a certain particle size enters the gaseous suspension roasting system and is subjected to high-temperature oxidizing roasting at the temperature of 900-1200 DEG C firstly, so that a large number of cracks are generated in ore particles, and subsequent acid-process phosphorus removal is facilitated; indirect heat exchange is conducted through circulating cooling water, the temperature of the ore is reduced to 600 DEG C or below, and reduction is conducted through reducing gas; spraying atomized water to reduce the temperature of the reduced ore, wherein most of non-magnetic iron ore is converted into magnetic iron ore Fe3O4 and gamma-Fe2O3; and finally, after four-stage air cooling, the product ore suitable for treatment can be obtained. The ore is subsequently subjected to magnetic separation to obtain high-phosphorus iron ore concentrate; and after the high-phosphorus iron ore concentrate is subjected to acid leaching phosphorus removal, qualified iron ore concentrate can be obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of mineral processing suspension roasting, and in particular relates to a gaseous suspension roasting device and method for high-phosphorus oolitic iron ore. Background Art

[0002] With the development of the global economy, the consumption of steel products is increasing. As a major producer and consumer of steel, my country must focus on domestic low-grade composite ores in order to alleviate the shortage of high-quality iron ore resources. As an important iron ore resource in my country, high-phosphorus oolitic iron ore is rich in reserves and is mainly distributed in Hubei, Hunan and other places. The proven reserves exceed 10 billion tons, of which about 4 billion tons have a high iron grade. High-phosphorus oolitic iron ore has complex mineral composition, fine mineral crystal size, high content of harmful element phosphorus, and unique oolitic structure. It is difficult to process and utilize with traditional mineral processing technology. It is recognized as the most difficult iron ore to be selected in the world.

[0003] In view of the characteristics of high-phosphorus oolitic iron ore, the current processes for increasing iron and reducing phosphorus mainly include magnetic separation, flotation, acid leaching, microbial leaching, direct reduction and their combined processes. Although after years of mineral processing tests and production practices, it is still difficult to obtain qualified products with traditional magnetic separation, gravity separation and flotation and their combined processes. Not only is the effect of reducing phosphorus unsatisfactory, but the phosphorus content is generally high (P>0.3%), and it cannot be directly used as a raw material for blast furnaces; in addition, the separation indicators are not ideal, the iron recovery rate is low, and it is difficult to achieve full recycling of resources. Roasting dephosphorization is a good choice. The roasting process of the traditional production process is realized in vertical kilns and rotary kilns.

[0004] In contrast, the vertical kiln production process is relatively backward. Vertical furnace roasting is mainly suitable for processing lump ore with a particle size of 15 to 75 mm. This process has problems such as low single-machine processing capacity, high energy consumption, long roasting time, uneven product quality, and is prone to over-burning and under-burning.

[0005] Although rotary kiln roasting is suitable for processing ores with smaller particle sizes, problems such as easy ring formation, unstable production, low operating rate and high energy consumption still exist. Summary of the invention

[0006] In view of the shortcomings of the prior art and to solve the above technical problems, the present invention provides a gaseous suspension roasting device and method for high-phosphorus oolitic iron ore, which combines high-temperature oxidation with medium-temperature reduction. High-temperature oxidation roasting (900-1200°C) can produce cracks inside the ore particles, which is convenient for subsequent acid leaching and phosphorus removal of the ore; the ore after high-temperature oxidation is indirectly heat-exchanged with circulating water and reduced to medium temperature (500-600°C), and then reacts with reducing gas; after the reduced ore is cooled by atomized spray water and four-stage air cooling, most of the non-magnetic iron ore is converted into magnetic iron ore Fe3O4 and γ-Fe2O3, which is convenient for subsequent magnetic separation. After high-phosphorus oolitic iron ore is subjected to high-temperature oxidation, medium-temperature reduction, magnetic separation enrichment, and acid leaching and phosphorus removal, qualified iron concentrate can be obtained.

[0007] A gaseous suspension roasting device for high-phosphorus oolitic iron ore, comprising a feeding system, an oxidation roasting system, an oxidation roasting sand cooling system, a reduction system, a reduction roasting sand cooling system and a dust removal and ash return system;

[0008] The discharge port of the feeding system is connected to the gas material inlet of the oxidation roasting system, the discharge port of the oxidation roasting system is connected to the feed port of the oxidation roasting sand cooling system, the gas material outlet of the oxidation roasting sand cooling system is connected to the gas material inlet of the reduction system, the gas material outlet of the reduction system is connected to the gas material inlet of the reduction roasting sand cooling system, and the reduction roasting sand cooling system is also provided with a discharge port;

[0009] The air inlet of the oxidation roasting system is divided into three inputs, the first one is connected with the air outlet of the oxidation roasting sand cooling system, the second one is connected with the air outlet of the reduction system, the third one is connected with the air outlet of the reduction roasting sand cooling system, the air outlet of the oxidation roasting system is connected with the air inlet of the dust removal and ash returning system; the ash returning port of the dust removal and ash returning system is connected with the back-blowing compressed air inlet of the oxidation roasting system, and the dust removal and ash returning system is also provided with an exhaust port.

[0010] The feeding system includes an ore bin and a loss-in-weight scale, and the discharge port at the bottom of the ore bin is connected to the feed port of the loss-in-weight scale;

[0011] The oxidation roasting system comprises a preheating cyclone A, a preheating cyclone B, a main furnace, a separation cyclone and a burner; the discharge port of the weight loss scale in the feeding system is connected to the gas inlet of the preheating cyclone A through the air outlet riser of the preheating cyclone B, and the gas inlet of the preheating cyclone A is connected to the air outlet riser of the preheating cyclone B; the discharge port of the preheating cyclone A is connected to the gas inlet of the preheating cyclone B through the air outlet riser of the separation cyclone, the gas inlet of the preheating cyclone B is connected to the air outlet of the separation cyclone, and the discharge port of the preheating cyclone B is connected to the feed port of the main furnace; the gas outlet of the main furnace is connected to the gas inlet of the separation cyclone, the air inlet of the main furnace is connected to the air outlet of the burner, and a fuel inlet is arranged at the bottom of the burner.

[0012] The oxidation roasting sand cooling system comprises a heat exchanger, an air lock valve A, a cyclone separator A, a cooling tower and a circulating water pump; the feed inlet of the heat exchanger is connected with the discharge port of the separation cyclone in the oxidation roasting system, the discharge port of the heat exchanger is connected with the feed inlet of the air lock valve A, the air outlet of the heat exchanger is connected with the gas material inlet of the cyclone separator A, the discharge port of the cyclone separator A is connected with the ash return port of the heat exchanger, and the air outlet of the cyclone separator A is connected with the air inlet of the main furnace in the oxidation roasting system; a fluidized compressed air inlet is arranged at the bottom of the heat exchanger, a water inlet and a water outlet are arranged on one side, the water inlet of the heat exchanger is connected with the water outlet of the circulating water pump, the water outlet of the heat exchanger is connected with the water inlet of the cooling tower, the water outlet of the cooling tower is connected with the water inlet of the circulating water pump, and a fluidized nitrogen inlet is arranged at the bottom of the air lock valve A.

[0013] The reduction system comprises a reduction tank, an air lock valve B and a cyclone separator B. A reduction gas inlet is arranged at the bottom of the reduction tank. The gas inlet of the reduction tank is connected to the gas outlet of the air lock valve A in the oxidation roasting sand cooling system. The gas outlet of the reduction tank is connected to the gas inlet of the cyclone separator B. The discharge port of the cyclone separator B is connected to the ash return port of the reduction tank. The discharge port of the reduction tank is connected to the feed port of the air lock valve B. The gas outlet of the cyclone separator B is connected to the gas inlet of the main furnace in the oxidation roasting system. A fluidized nitrogen inlet is arranged at the bottom of the air lock valve B.

[0014] The reduction roasted sand cooling system comprises a cooling cyclone A, a cooling cyclone B, a cooling cyclone C and a cooling cyclone D; the gas outlet of the air lock valve B in the reduction system is connected to the gas inlet of the cooling cyclone A through the air outlet riser of the cooling cyclone B, the gas inlet of the cooling cyclone A is connected to the gas outlet of the cooling cyclone B, the outlet of the cooling cyclone A is connected to the gas inlet of the cooling cyclone B through the air outlet riser of the cooling cyclone C, and the gas outlet of the cooling cyclone A is connected to the gas inlet of the main furnace in the oxidation roasting system; A water inlet is arranged on the air outlet riser of cooling cyclone B, the air inlet of cooling cyclone B is connected with the air outlet of cooling cyclone C, and the outlet of cooling cyclone B is connected with the air inlet of cooling cyclone C through the air outlet riser of cooling cyclone D; the air inlet of cooling cyclone C is connected with the air outlet of cooling cyclone D, and the outlet of cooling cyclone C is connected with the air inlet of cooling cyclone D; a discharge port is arranged at the bottom of cooling cyclone D, and the air inlet of cooling cyclone D is the main combustion air inlet of the reduction roasted sand cooling system.

[0015] The dust removal and ash return system comprises a bag filter, an air chute, a powder feeder, an induced draft fan and a smoke duct; the air inlet of the bag filter is connected to the air outlet of the preheating cyclone A in the oxidation roasting system, the air outlet of the bag filter is connected to the air inlet of the induced draft fan, and the discharge port of the bag filter is connected to the feed port of the air chute; the discharge port of the air chute is connected to the feed port of the powder feeder, a back-blowing compressed air inlet is provided on one side of the powder feeder, and an ash return port is provided on the other side, the ash return port of the powder feeder is connected to the air inlet of the separation cyclone, and the air inlet of the separation cyclone is the back-blowing compressed air inlet of the oxidation roasting system; the air outlet of the induced draft fan is connected to the air inlet of the smoke duct, and an exhaust port is provided on the top of the smoke duct.

[0016] The loss-in-weight scale comprises a weighing device and a spiral feeding device, and has the functions of accurately measuring the amount of material discharged and feeding.

[0017] The preheating cyclone A, preheating cyclone B, separation cyclone, cooling cyclone A, cooling cyclone B, cooling cyclone C and cooling cyclone D all adopt cyclone separators. The upper part of the cyclone separator is a cylindrical structure and the lower part is a conical structure, which has the function of gas-solid separation.

[0018] A spray head is arranged at the water inlet on the air outlet riser of the cooling cyclone B, and the spray head has an atomization function.

[0019] A method for gaseous suspension roasting of high-phosphorus oolitic iron ore is implemented by using the above device, and specifically comprises the following steps:

[0020] Step 1. After the raw ore is crushed, the obtained raw material is transported to the feed pipe of the preheating cyclone A through the ore bin and the weight loss scale;

[0021] Step 2. The raw materials in the feed pipe of the preheating cyclone A are brought into the preheating cyclone A through the feed pipe under the action of the airflow for the first preheating, and then separated from the flue gas; the raw materials after the first preheating are mixed with the flue gas from the separation cyclone, brought into the preheating cyclone B for the second preheating, and then separated from the flue gas to obtain the pre-roasted material;

[0022] Step 3. The pre-roasted material enters the main furnace through a pipeline, and is oxidatively roasted in an oxidative atmosphere formed by combustion of gas or pulverized coal and under a heating state to obtain roasted sand after oxidative roasting, which is mixed with the hot flue gas of the main furnace and enters a separation cyclone for flue gas separation;

[0023] Step 4. The roasted sand after separation of flue gas enters the heat exchanger, uses air as fluidizing air, and is cooled to below 600°C through a cooling tower and a circulating water pump to obtain cooled roasted sand;

[0024] Step 5. The cooled roasted sand enters the reduction tank through the air lock valve A and the pipeline, is reduced under the action of the reducing gas and fluidized nitrogen in the reduction tank, and the residence time of the roasted sand is extended to obtain the reduced roasted sand;

[0025] Step 6. The reduced roasted sand is discharged from the reduction tank through the air lock valve B and the pipeline into the reduction roasted sand cooling system for cooling. The cooling process is carried out step by step in the cooling cyclone A, the cooling cyclone B, the cooling cyclone C, and the cooling cyclone D. The roasted sand and the cold air achieve complete countercurrent heat exchange to obtain ore suitable for treatment. The air used for cooling comes from the atmosphere.

[0026] Step 7. The dust-laden flue gas discharged from the preheating cyclone A enters the bag filter through the pipeline for dust removal. The obtained dust is collected in the air chute at the bottom of the bag filter. The collected dust is returned to the separation cyclone through the compressed air and the powder conveyor to realize closed-circuit dust collection. The flue gas after dust removal and purification is sent into the smoke duct through the induced draft fan for discharge.

[0027] In the step 1, the raw ore is high-phosphorus oolitic iron ore, and the particle size of the raw material obtained after crushing is ≤500 mm.

[0028] In step 2, the first preheating temperature is 250°C to 360°C, and the second preheating temperature is 500°C to 750°C.

[0029] In the step 3, the calcination temperature is 900° C. to 1200° C., and the calcination time is 2s to 3s.

[0030] In step 5, the residence time of the roasted sand is 15 min to 60 min.

[0031] In step 6, the amount of water sprayed on the air outlet riser of the cooling cyclone B is 5% to 8% of the mass of the ore. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic structural diagram of a gaseous suspension roasting device for treating high-phosphorus oolitic iron ore according to the present invention;

[0033] Among them, 1-ore bin, 2-loss-in-weight scale, 3-preheating cyclone A, 4-preheating cyclone B, 5-main furnace, 6-separation cyclone, 7-heat exchanger, 8-air lock valve A, 9-reduction tank, 10-air lock valve B, 11-cooling cyclone A, 12-cooling cyclone B, 13-cooling cyclone C, 14-cooling cyclone D, 15-bag dust collector, 16-air chute, 17-powder conveyor, 18-induced draft fan, 19-smoke duct, 20-cyclone separator A, 21-cyclone separator B, 22-burner, 23-cooling tower, 24-circulating water pump. DETAILED DESCRIPTION

[0034] Example 1

[0035] A gaseous suspension roasting device for high-phosphorus oolitic iron ore, the schematic diagram of which is shown in FIG. Figure 1 As shown, it includes a feeding system, an oxidation roasting system, an oxidation roasting sand cooling system, a reduction system, a reduction roasting sand cooling system and a dust removal and ash return system;

[0036] The discharge port of the feeding system is connected to the gas material inlet of the oxidation roasting system, the discharge port of the oxidation roasting system is connected to the feed port of the oxidation roasting sand cooling system, the gas material outlet of the oxidation roasting sand cooling system is connected to the gas material inlet of the reduction system, the gas material outlet of the reduction system is connected to the gas material inlet of the reduction roasting sand cooling system, and the reduction roasting sand cooling system is also provided with a discharge port;

[0037] The air inlet of the oxidation roasting system is divided into three inputs, the first one is connected with the air outlet of the oxidation roasting sand cooling system, the second one is connected with the air outlet of the reduction system, the third one is connected with the air outlet of the reduction roasting sand cooling system, the air outlet of the oxidation roasting system is connected with the air inlet of the dust removal and ash returning system; the ash returning port of the dust removal and ash returning system is connected with the back-blowing compressed air inlet of the oxidation roasting system, and the dust removal and ash returning system is also provided with an exhaust port.

[0038] The feeding system includes an ore bin 1 and a loss-in-weight scale 2, wherein the discharge port at the bottom of the ore bin 1 is connected to the feed port of the loss-in-weight scale 2. The loss-in-weight scale 2 includes a weighing device and a spiral feeding device, and has the functions of accurately measuring the amount of material discharged and feeding.

[0039] The oxidation roasting system comprises a preheating cyclone A3, a preheating cyclone B4, a main furnace 5, a separation cyclone 6 and a burner 22; the discharge port of the weight loss scale 2 in the feeding system is connected to the gas inlet of the preheating cyclone A3 through the air outlet riser of the preheating cyclone B4, the gas inlet of the preheating cyclone A3 is connected to the air outlet riser of the preheating cyclone B4, the discharge port of the preheating cyclone A3 is connected to the gas inlet of the preheating cyclone B4 through the air outlet riser of the separation cyclone 6, the gas inlet of the preheating cyclone B4 is connected to the air outlet of the separation cyclone 6, the discharge port of the preheating cyclone B4 is connected to the feed port of the main furnace 5; the gas outlet of the main furnace 5 is connected to the gas inlet of the separation cyclone 6, the air inlet of the main furnace 5 is connected to the air outlet of the burner 22, and a fuel inlet is arranged at the bottom of the burner 22. Among them, the preheating cyclone A3, the preheating cyclone B4, and the separation cyclone 6 all adopt cyclone separators, the upper part of the cyclone separator is a cylindrical structure, and the lower part is a conical structure, which has the function of gas-solid separation.

[0040] The oxidation roasting sand cooling system includes a heat exchanger 7, an air lock valve A8, a cyclone separator A20, a cooling tower 23 and a circulating water pump 24; the feed port of the heat exchanger 7 is connected to the discharge port of the separation cyclone 6 in the oxidation roasting system, the discharge port of the heat exchanger 7 is connected to the feed port of the air lock valve A8, the air outlet of the heat exchanger 7 is connected to the air material inlet of the cyclone separator A20, and the discharge port of the cyclone separator A20 is connected to the ash return port of the heat exchanger 7 The air outlet of the cyclone separator A20 is connected to the air inlet of the main furnace 5 in the oxidation roasting system; the bottom of the heat exchanger 7 is provided with a fluidized compressed air inlet, and one side is provided with a water inlet and a water outlet. The water inlet of the heat exchanger 7 is connected to the water outlet of the circulating water pump 24, and the water outlet of the heat exchanger 7 is connected to the water inlet of the cooling tower 23. The water outlet of the cooling tower 23 is connected to the water inlet of the circulating water pump 24. The bottom of the air lock valve A8 is provided with a fluidized nitrogen inlet. Among them, the upper part of the cyclone separator A20 is a cylindrical structure and the lower part is a conical structure, which has the function of gas-solid separation.

[0041] The reduction system includes a reduction tank 9, an air lock valve B10 and a cyclone separator B21, a reduction gas inlet is arranged at the bottom of the reduction tank 9, the gas material inlet of the reduction tank 9 is connected to the gas material outlet of the air lock valve A8 in the oxidation roasting sand cooling system, the gas outlet of the reduction tank 9 is connected to the gas material inlet of the cyclone separator B21, the material outlet of the cyclone separator B21 is connected to the ash return port of the reduction tank 9, the material outlet of the reduction tank 9 is connected to the material inlet of the air lock valve B10, the gas outlet of the cyclone separator B21 is connected to the gas inlet of the main furnace 5 in the oxidation roasting system; and a fluidized nitrogen inlet is arranged at the bottom of the air lock valve B10. The upper part of the cyclone separator B21 is a cylindrical structure and the lower part is a conical structure, which has the function of gas-solid separation.

[0042] The reduction roasted sand cooling system comprises a cooling cyclone A11, a cooling cyclone B12, a cooling cyclone C13 and a cooling cyclone D14; the gas outlet of the air lock valve B10 in the reduction system is connected to the gas inlet of the cooling cyclone A11 through the air outlet riser of the cooling cyclone B12, the gas inlet of the cooling cyclone A11 is connected to the gas outlet of the cooling cyclone B12, the material outlet of the cooling cyclone A11 is connected to the gas inlet of the cooling cyclone B12 through the air outlet riser of the cooling cyclone C13, and the gas outlet of the cooling cyclone A11 is connected to the air inlet of the main furnace 5 in the oxidation roasting system The air inlet of the cooling cyclone B12 is connected with the air outlet of the cooling cyclone C13, and the outlet of the cooling cyclone B12 is connected with the air inlet of the cooling cyclone C13 through the air outlet riser of the cooling cyclone D14; the air inlet of the cooling cyclone C13 is connected with the air outlet of the cooling cyclone D14, and the outlet of the cooling cyclone C13 is connected with the air inlet of the cooling cyclone D14; a discharge port is provided at the bottom of the cooling cyclone D14, and the air inlet of the cooling cyclone D14 is the main combustion air inlet of the reduction roasted sand cooling system. Among them, cooling cyclone A11, cooling cyclone B12, cooling cyclone C13, and cooling cyclone D14 use cyclone separators. The upper part of the cyclone separator is a cylindrical structure and the lower part is a conical structure, which has the function of gas-solid separation; a spray head is arranged at the water inlet on the air outlet riser of the cooling cyclone B12, and the spray head has the function of atomization.

[0043] The dust removal and ash return system includes a bag dust collector 15, an air chute 16, a powder feeder 17, an induced draft fan 18 and a smoke duct 19; the air inlet of the bag dust collector 15 is connected to the air outlet of the preheating cyclone A3 in the oxidation roasting system, the air outlet of the bag dust collector 15 is connected to the air inlet of the induced draft fan 18, and the discharge port of the bag dust collector 15 is connected to the feed port of the air chute 16; the discharge port of the air chute 16 is connected to the feed port of the powder feeder 17, a back-blowing compressed air inlet is provided on one side of the powder feeder 17, and an ash return port is provided on the other side, the ash return port of the powder feeder 17 is connected to the air inlet of the separation cyclone 6, and the air inlet of the separation cyclone 6 is the back-blowing compressed air inlet of the oxidation roasting system; the air outlet of the induced draft fan 18 is connected to the air inlet of the smoke duct 19, and an exhaust port is provided on the top of the smoke duct 19.

[0044] Example 2

[0045] The raw material used in this embodiment is high-phosphorus oolitic iron ore, and the chemical composition is shown in Table 1:

[0046] Table 1 Chemical composition of raw materials of Example 2

[0047]

[0048] A gaseous suspension roasting method for high-phosphorus oolitic iron ore, using the device in Example 1, comprises the following steps:

[0049] Step 1. After the raw material is crushed to a particle size of ≤500 mm, the obtained raw material is transported to the feed pipe of the preheating cyclone A3 through the ore bin 1 and the weight loss scale 2.

[0050] Step 2. The raw materials in the feed pipe of the preheating cyclone A3 are brought into the preheating cyclone A3 through the feed pipe under the action of the airflow for the first preheating at a temperature of 250°C, and then separated from the flue gas; the raw materials after the first preheating are mixed with the flue gas from the separation cyclone 6, and brought into the preheating cyclone B4 for the second preheating at a temperature of 500°C, and then separated from the flue gas to obtain the pre-roasted material.

[0051] Step 3. The pre-roasted material enters the main furnace 5 through a pipeline, and is subjected to oxidative roasting in an oxidizing atmosphere formed by combustion of gas or pulverized coal and under a heating state. The roasting temperature is 900°C and the roasting time is 2s. The roasted sand is obtained after oxidative roasting and mixed with the hot flue gas of the main furnace 5 and enters the separation cyclone 6 for flue gas separation.

[0052] Step 4. The roasted sand after separation of the flue gas enters the heat exchanger 7, and uses air as fluidizing air. The material is cooled to below 600° C. through the cooling tower 23 and the circulating water pump 24 to obtain cooled roasted sand.

[0053] Step 5. The cooled roasted sand enters the reduction tank 9 through the air lock valve A8 and the pipeline, and is reduced under the action of the reducing gas and fluidized nitrogen in the reduction tank 9, and the roasted sand residence time is extended to 15 minutes to obtain the reduced roasted sand.

[0054] Step 6. The reduced roasted sand is unloaded from the reduction tank 9 through the air lock valve B10 and the pipeline into the reduction roasted sand cooling system for cooling. The cooling process is carried out step by step in the cooling cyclone A11, the cooling cyclone B12, the cooling cyclone C13, and the cooling cyclone D14. The roasted sand and the cold air achieve complete countercurrent heat exchange. The amount of water sprayed on the air outlet riser of the cooling cyclone B is 5% of the mass of the ore, and ore suitable for treatment is obtained. The air used for cooling comes from the atmosphere.

[0055] The obtained ore can be subjected to magnetic separation and leaching process to obtain iron concentrate with technical indicators of TFe grade of 64.89%, recovery rate of 93.86% and phosphorus content of 0.19%.

[0056] Step 7. The dust-containing flue gas discharged from the preheating cyclone A3 enters the bag filter 15 through the pipeline for dust removal, and the obtained dust is collected in the air chute 16 at the bottom of the bag filter. The collected dust is returned to the separation cyclone 6 through the compressed air and the powder conveyor 17, thereby realizing closed-circuit dust collection; the flue gas after dust removal and purification is sent to the smoke duct 19 through the induced draft fan 18 for discharge.

[0057] Example 3

[0058] The raw material used in this embodiment is high-phosphorus oolitic iron ore, and the chemical composition is shown in Table 2:

[0059] Table 2 Chemical composition of raw materials of Example 3

[0060]

[0061] A gaseous suspension roasting method for high-phosphorus oolitic iron ore, using the device in Example 1, comprises the following steps:

[0062] Step 1. After the raw material is crushed to a particle size of ≤500 mm, the obtained raw material is transported to the feed pipe of the preheating cyclone A3 through the ore bin 1 and the weight loss scale 2.

[0063] Step 2. The raw materials in the feed pipe of the preheating cyclone A3 are brought into the preheating cyclone A3 through the feed pipe under the action of the airflow for the first preheating at a temperature of 300°C, and then separated from the flue gas; the raw materials after the first preheating are mixed with the flue gas from the separation cyclone 6, and brought into the preheating cyclone B4 for the second preheating at a temperature of 600°C, and then separated from the flue gas to obtain the pre-roasted material.

[0064] Step 3. The pre-roasted material enters the main furnace 5 through a pipeline, and is subjected to oxidative roasting in an oxidizing atmosphere formed by combustion of gas or pulverized coal and under a heating state. The roasting temperature is 1000°C, and the roasting time is 2.4s. The roasted sand is obtained after oxidative roasting and mixed with the hot flue gas of the main furnace 5 and enters the separation cyclone 6 for flue gas separation.

[0065] Step 4. The roasted sand after separation of the flue gas enters the heat exchanger 7, and uses air as fluidizing air. The material is cooled to below 600° C. through the cooling tower 23 and the circulating water pump 24 to obtain cooled roasted sand.

[0066] Step 5. The cooled roasted sand enters the reduction tank 9 through the air lock valve A8 and the pipeline, and is reduced under the action of the reducing gas and fluidized nitrogen in the reduction tank 9, and the roasted sand residence time is extended to 20 minutes to obtain the reduced roasted sand.

[0067] Step 6. The reduced roasted sand is unloaded from the reduction tank 9 through the air lock valve B10 and the pipeline into the reduction roasted sand cooling system for cooling. The cooling process is carried out step by step in the cooling cyclone A11, the cooling cyclone B12, the cooling cyclone C13, and the cooling cyclone D14. The roasted sand and the cold air achieve complete countercurrent heat exchange. The amount of water sprayed on the air outlet riser of the cooling cyclone B is 6% of the mass of the ore, and the ore suitable for treatment is obtained. The air used for cooling comes from the atmosphere.

[0068] The obtained ore can be subjected to magnetic separation and leaching process to obtain iron concentrate with technical indicators of TFe grade of 63.36%, recovery rate of 93.79% and phosphorus content of 0.09%.

[0069] Step 7. The dust-containing flue gas discharged from the preheating cyclone A3 enters the bag filter 15 through the pipeline for dust removal, and the obtained dust is collected in the air chute 16 at the bottom of the bag filter. The collected dust is returned to the separation cyclone 6 through the compressed air and the powder conveyor 17, thereby realizing closed-circuit dust collection; the flue gas after dust removal and purification is sent to the smoke duct 19 through the induced draft fan 18 for discharge.

[0070] Example 4

[0071] The raw material used in this embodiment is high-phosphorus oolitic iron ore, and the chemical composition is shown in Table 3:

[0072] Table 3 Chemical composition of raw materials of Example 4

[0073]

[0074] A gaseous suspension roasting method for high-phosphorus oolitic iron ore, using the device in Example 1, comprises the following steps:

[0075] Step 1. After the raw material is crushed to a particle size of ≤500 mm, the obtained raw material is transported to the feed pipe of the preheating cyclone A3 through the ore bin 1 and the weight loss scale 2.

[0076] Step 2. The raw materials in the feed pipe of the preheating cyclone A3 are brought into the preheating cyclone A3 through the feed pipe under the action of the airflow for the first preheating at a temperature of 320°C, and then separated from the flue gas; the raw materials after the first preheating are mixed with the flue gas from the separation cyclone 6, and brought into the preheating cyclone B4 for the second preheating at a temperature of 650°C, and then separated from the flue gas to obtain the pre-roasted material.

[0077] Step 3. The pre-roasted material enters the main furnace 5 through a pipeline, and is subjected to oxidative roasting in an oxidizing atmosphere formed by combustion of gas or pulverized coal and under a heating state. The roasting temperature is 1100°C and the roasting time is 2.8s. The roasted sand is obtained after oxidative roasting and mixed with the hot flue gas of the main furnace 5 and enters the separation cyclone 6 for flue gas separation.

[0078] Step 4. The roasted sand after separation of the flue gas enters the heat exchanger 7, and uses air as fluidizing air. The material is cooled to below 600° C. through the cooling tower 23 and the circulating water pump 24 to obtain cooled roasted sand.

[0079] Step 5. The cooled roasted sand enters the reduction tank 9 through the air lock valve A8 and the pipeline, and is reduced under the action of the reducing gas and fluidized nitrogen in the reduction tank 9, and the roasted sand residence time is extended to 30 minutes to obtain the reduced roasted sand.

[0080] Step 6. The reduced roasted sand is unloaded from the reduction tank 9 through the air lock valve B10 and the pipeline into the reduction roasted sand cooling system for cooling. The cooling process is carried out step by step in the cooling cyclone A11, the cooling cyclone B12, the cooling cyclone C13, and the cooling cyclone D14. The roasted sand and the cold air achieve complete countercurrent heat exchange. The amount of water sprayed on the air outlet riser of the cooling cyclone B is 7% of the mass of the ore, and the ore suitable for treatment is obtained. The air used for cooling comes from the atmosphere.

[0081] The obtained ore can be subjected to magnetic separation and leaching process to obtain iron concentrate with technical indicators of TFe grade of 62.46%, recovery rate of 92.58% and phosphorus content of 0.07%.

[0082] Step 7. The dust-containing flue gas discharged from the preheating cyclone A3 enters the bag filter 15 through the pipeline for dust removal, and the obtained dust is collected in the air chute 16 at the bottom of the bag filter. The collected dust is returned to the separation cyclone 6 through the compressed air and the powder conveyor 17, thereby realizing closed-circuit dust collection; the flue gas after dust removal and purification is sent to the smoke duct 19 through the induced draft fan 18 for discharge.

[0083] Example 5

[0084] The raw material used in this embodiment is high-phosphorus oolitic iron ore, and the chemical composition is shown in Table 4:

[0085] Table 4 Chemical composition of raw materials of Example 5

[0086]

[0087] A gaseous suspension roasting method for high-phosphorus oolitic iron ore, using the device in Example 1, comprises the following steps:

[0088] Step 1. After the raw material is crushed to a particle size of ≤500 mm, the obtained raw material is transported to the feed pipe of the preheating cyclone A3 through the ore bin 1 and the weight loss scale 2.

[0089] Step 2. The raw materials in the feed pipe of the preheating cyclone A3 are brought into the preheating cyclone A3 through the feed pipe under the action of the airflow for the first preheating at a temperature of 360°C, and then separated from the flue gas; the raw materials after the first preheating are mixed with the flue gas from the separation cyclone 6, and brought into the preheating cyclone B4 for the second preheating at a temperature of 750°C, and then separated from the flue gas to obtain the pre-roasted material.

[0090] Step 3. The pre-roasted material enters the main furnace 5 through a pipeline, and is subjected to oxidative roasting in an oxidizing atmosphere formed by combustion of gas or pulverized coal and under a heating state. The roasting temperature is 1200°C and the roasting time is 3s. The roasted sand after oxidative roasting is obtained and mixed with the hot flue gas of the main furnace 5 and enters the separation cyclone 6 for flue gas separation.

[0091] Step 4. The roasted sand after separation of the flue gas enters the heat exchanger 7, and uses air as fluidizing air. The material is cooled to below 600° C. through the cooling tower 23 and the circulating water pump 24 to obtain cooled roasted sand.

[0092] Step 5. The cooled roasted sand enters the reduction tank 9 through the air lock valve A8 and the pipeline, and is reduced under the action of the reducing gas and fluidized nitrogen in the reduction tank 9, and the roasted sand residence time is extended to 40 minutes to obtain the reduced roasted sand.

[0093] Step 6. The reduced roasted sand is unloaded from the reduction tank 9 through the air lock valve B10 and the pipeline into the reduction roasted sand cooling system for cooling. The cooling process is carried out step by step in the cooling cyclone A11, the cooling cyclone B12, the cooling cyclone C13, and the cooling cyclone D14. The roasted sand and the cold air achieve complete countercurrent heat exchange. The amount of water sprayed on the air outlet riser of the cooling cyclone B is 8% of the mass of the ore, and ore suitable for treatment is obtained. The air used for cooling comes from the atmosphere.

[0094] The obtained ore can be subjected to magnetic separation and leaching process to obtain iron concentrate with technical indicators of TFe grade of 63.86%, recovery rate of 89.37% and phosphorus content of 0.15%.

[0095] Step 7. The dust-containing flue gas discharged from the preheating cyclone A3 enters the bag filter 15 through the pipeline for dust removal, and the obtained dust is collected in the air chute 16 at the bottom of the bag filter. The collected dust is returned to the separation cyclone 6 through the compressed air and the powder conveyor 17, thereby realizing closed-circuit dust collection; the flue gas after dust removal and purification is sent to the smoke duct 19 through the induced draft fan 18 for discharge.

Claims

1. A gaseous suspension roasting device for high-phosphorus oolitic iron ore, characterized in that: It includes a feeding system, an oxidation roasting system, an oxidation roasting sand cooling system, a reduction system, a reduction roasting sand cooling system and a dust removal and ash return system; The discharge port of the feeding system is connected to the gas material inlet of the oxidation roasting system, the discharge port of the oxidation roasting system is connected to the feed port of the oxidation roasting sand cooling system, the gas material outlet of the oxidation roasting sand cooling system is connected to the gas material inlet of the reduction system, the gas material outlet of the reduction system is connected to the gas material inlet of the reduction roasting sand cooling system, and the reduction roasting sand cooling system is also provided with a discharge port; The air inlet of the oxidation roasting system is divided into three inputs, the first one is connected with the air outlet of the oxidation roasting sand cooling system, the second one is connected with the air outlet of the reduction system, the third one is connected with the air outlet of the reduction roasting sand cooling system, the air outlet of the oxidation roasting system is connected with the air inlet of the dust removal and ash returning system; the ash returning port of the dust removal and ash returning system is connected with the back-blowing compressed air inlet of the oxidation roasting system, and the dust removal and ash returning system is also provided with an exhaust port.

2. The gaseous suspension roasting device for high-phosphorus oolitic iron ore according to claim 1, characterized in that: The feeding system includes an ore bin and a loss-in-weight scale, and the discharge port at the bottom of the ore bin is connected to the feed port of the loss-in-weight scale; The oxidation roasting system comprises a preheating cyclone A, a preheating cyclone B, a main furnace, a separation cyclone and a burner; the discharge port of the weight loss scale in the feeding system is connected to the gas inlet of the preheating cyclone A through the air outlet riser of the preheating cyclone B, and the gas inlet of the preheating cyclone A is connected to the air outlet riser of the preheating cyclone B; the discharge port of the preheating cyclone A is connected to the gas inlet of the preheating cyclone B through the air outlet riser of the separation cyclone, the gas inlet of the preheating cyclone B is connected to the air outlet of the separation cyclone, and the discharge port of the preheating cyclone B is connected to the feed port of the main furnace; the gas outlet of the main furnace is connected to the gas inlet of the separation cyclone, the air inlet of the main furnace is connected to the air outlet of the burner, and a fuel inlet is arranged at the bottom of the burner.

3. The gaseous suspension roasting device for high-phosphorus oolitic iron ore according to claim 2, characterized in that: The oxidation roasting sand cooling system comprises a heat exchanger, an air lock valve A, a cyclone separator A, a cooling tower and a circulating water pump; the feed inlet of the heat exchanger is connected to the discharge port of the separation cyclone in the oxidation roasting system, the discharge port of the heat exchanger is connected to the feed inlet of the air lock valve A, the air outlet of the heat exchanger is connected to the gas material inlet of the cyclone separator A, the discharge port of the cyclone separator A is connected to the ash return port of the heat exchanger, and the air outlet of the cyclone separator A is connected to the air inlet of the main furnace in the oxidation roasting system; a fluidized compressed air inlet is arranged at the bottom of the heat exchanger, a water inlet and a water outlet are arranged on one side, the water inlet of the heat exchanger is connected to the water outlet of the circulating water pump, the water outlet of the heat exchanger is connected to the water inlet of the cooling tower, the water outlet of the cooling tower is connected to the water inlet of the circulating water pump, and a fluidized nitrogen inlet is arranged at the bottom of the air lock valve A; The reduction system comprises a reduction tank, an air lock valve B and a cyclone separator B. A reduction gas inlet is arranged at the bottom of the reduction tank. The gas inlet of the reduction tank is connected to the gas outlet of the air lock valve A in the oxidation roasting sand cooling system. The gas outlet of the reduction tank is connected to the gas inlet of the cyclone separator B. The discharge port of the cyclone separator B is connected to the ash return port of the reduction tank. The discharge port of the reduction tank is connected to the feed port of the air lock valve B. The gas outlet of the cyclone separator B is connected to the gas inlet of the main furnace in the oxidation roasting system. A fluidized nitrogen inlet is arranged at the bottom of the air lock valve B.

4. The gaseous suspension roasting device for high-phosphorus oolitic iron ore according to claim 3, characterized in that: The reduction roasted sand cooling system comprises a cooling cyclone A, a cooling cyclone B, a cooling cyclone C and a cooling cyclone D; the gas outlet of the air lock valve B in the reduction system is connected to the gas inlet of the cooling cyclone A through the air outlet riser of the cooling cyclone B, the gas inlet of the cooling cyclone A is connected to the gas outlet of the cooling cyclone B, the outlet of the cooling cyclone A is connected to the gas inlet of the cooling cyclone B through the air outlet riser of the cooling cyclone C, and the gas outlet of the cooling cyclone A is connected to the gas inlet of the main furnace in the oxidation roasting system; A water inlet is arranged on the air outlet riser of the cooling cyclone B, the gas inlet of the cooling cyclone B is connected with the air outlet of the cooling cyclone C, and the discharge port of the cooling cyclone B is connected with the gas inlet of the cooling cyclone C through the air outlet riser of the cooling cyclone D; the gas inlet of the cooling cyclone C is connected with the air outlet of the cooling cyclone D, and the discharge port of the cooling cyclone C is connected with the gas inlet of the cooling cyclone D; a discharge port is arranged at the bottom of the cooling cyclone D, and the gas inlet of the cooling cyclone D is the main combustion air inlet of the reduction roasted sand cooling system; The dust removal and ash return system comprises a bag filter, an air chute, a powder feeder, an induced draft fan and a smoke duct; the air inlet of the bag filter is connected to the air outlet of the preheating cyclone A in the oxidation roasting system, the air outlet of the bag filter is connected to the air inlet of the induced draft fan, and the discharge port of the bag filter is connected to the feed port of the air chute; the discharge port of the air chute is connected to the feed port of the powder feeder, a back-blowing compressed air inlet is provided on one side of the powder feeder, and an ash return port is provided on the other side, the ash return port of the powder feeder is connected to the air inlet of the separation cyclone, and the air inlet of the separation cyclone is the back-blowing compressed air inlet of the oxidation roasting system; the air outlet of the induced draft fan is connected to the air inlet of the smoke duct, and an exhaust port is provided on the top of the smoke duct.

5. The gaseous suspension roasting device for high-phosphorus oolitic iron ore according to claim 4, characterized in that: The loss-in-weight scale comprises a weighing device and a spiral feeding device, and has the functions of accurately measuring the amount of material discharged and feeding; The preheating cyclone A, preheating cyclone B, separation cyclone, cooling cyclone A, cooling cyclone B, cooling cyclone C and cooling cyclone D all adopt cyclone separators. The upper part of the cyclone separator is a cylindrical structure and the lower part is a conical structure, which has the function of gas-solid separation.

6. The gaseous suspension roasting device for high-phosphorus oolitic iron ore according to claim 4, characterized in that: A spray head is arranged at the water inlet on the air outlet riser of the cooling cyclone B, and the spray head has an atomization function.

7. A method for gaseous suspension roasting of high-phosphorus oolitic iron ore, implemented by the device of claim 5, characterized in that: The specific steps include: Step 1. After the raw ore is crushed, the obtained raw material is transported to the feed pipe of the preheating cyclone A through the ore bin and the weight loss scale; Step 2. The raw materials in the feed pipe of the preheating cyclone A are brought into the preheating cyclone A through the feed pipe under the action of the airflow for the first preheating, and then separated from the flue gas; the raw materials after the first preheating are mixed with the flue gas from the separation cyclone, brought into the preheating cyclone B for the second preheating, and then separated from the flue gas to obtain the pre-roasted material; Step 3. The pre-roasted material enters the main furnace through a pipeline, and is oxidatively roasted in an oxidative atmosphere formed by combustion of gas or pulverized coal and under a heating state to obtain roasted sand after oxidative roasting, which is mixed with the hot flue gas of the main furnace and enters a separation cyclone for flue gas separation; Step 4. The roasted sand after separation of flue gas enters the heat exchanger, uses air as fluidizing air, and is cooled to below 600°C through a cooling tower and a circulating water pump to obtain cooled roasted sand; Step 5. The cooled roasted sand enters the reduction tank through the air lock valve A and the pipeline, is reduced under the action of the reducing gas and fluidized nitrogen in the reduction tank, and the residence time of the roasted sand is extended to obtain the reduced roasted sand; Step 6. The reduced roasted sand is discharged from the reduction tank through the air lock valve B and the pipeline into the reduction roasted sand cooling system for cooling. The cooling process is carried out step by step in the cooling cyclone A, the cooling cyclone B, the cooling cyclone C, and the cooling cyclone D. The roasted sand and the cold air achieve complete countercurrent heat exchange to obtain ore suitable for treatment. The air used for cooling comes from the atmosphere. Step 7. The dust-laden flue gas discharged from the preheating cyclone A enters the bag filter through the pipeline for dust removal. The obtained dust is collected in the air chute at the bottom of the bag filter. The collected dust is returned to the separation cyclone through the compressed air and the powder conveyor to realize closed-circuit dust collection. The flue gas after dust removal and purification is sent into the smoke duct through the induced draft fan for discharge.

8. The method for gaseous suspension roasting of high-phosphorus oolitic iron ore according to claim 7, characterized in that: In the step 1, the raw ore is high-phosphorus oolitic iron ore, and the particle size of the raw material obtained after crushing is ≤500mm; In step 2, the first preheating temperature is 250°C to 360°C, and the second preheating temperature is 500°C to 750°C.

9. The method for gaseous suspension roasting of high-phosphorus oolitic iron ore according to claim 7, characterized in that: In the step 3, the calcination temperature is 900° C. to 1200° C., and the calcination time is 2s to 3s.

10. The method for gaseous suspension roasting of high-phosphorus oolitic iron ore according to claim 7, characterized in that: In step 5, the residence time of the roasted sand is 15 min to 60 min; In step 6, the amount of water sprayed on the air outlet riser of the cooling cyclone B is 5% to 8% of the mass of the ore.

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