Iron ore pre-oxidation roasting in-situ sulfur fixation device and method
By using the preoxidation roasting process before iron ore roasting, calcite and dolomite can be used to achieve in-situ solid sulfur, the problem of SO2 pollution during high sulfhydryl iron ore roasting is solved, cost and pollution are reduced, and roasting efficiency is improved.
Patent Information
- Application Number
- CN202411635737.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-15
- Publication Date
- 2025-02-18
AI Technical Summary
High sulfur hard-to-select iron ore produces SO2 polluted gas during roasting, resulting in environmental pollution and equipment corrosion. The existing sulfur solidification technology is inefficient and costly.
By introducing a preoxidation and roasting process before reduction and roasting, calcite and dolomite naturally occurring in iron ore are used as in-situ sulfur solid agents to convert SO2 into stable solid sulfide under an oxidative atmosphere to achieve in-situ sulfur solid.
Reliance on external sulfur solid agents is reduced, production costs are reduced, roasting efficiency is improved, equipment corrosion problems are reduced, and SO2 is effectively suppressed and environmental pollution is reduced.
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Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of mineral processing and relates to a device and method for in-situ sulfur fixation of iron ore pre-oxidation roasting. Background Art
[0002] Iron ore is a key raw material for steel production, but high-sulfur and difficult-to-select iron ore easily generates sulfur dioxide (SO 2 ) and other harmful gases, leading to environmental pollution and equipment corrosion. The existing roasting process often uses reduction roasting, but in a reducing atmosphere, sulfides are easily decomposed into hydrogen sulfide (H 2 S) or disulfide (S 2 ), the sulfur fixation reaction is not sufficient, resulting in sulfur emissions being difficult to control. In order to reduce sulfur emissions, limestone or quicklime is usually added as an external sulfur fixation agent. However, this increases production costs, and the sulfur fixation efficiency is not high, and residual sulfur still exists.
[0003] Studies have shown that pre-oxidation treatment can improve the reduction performance of ore, but existing technologies have limited research on sulfur fixation in the pre-oxidation stage, especially the potential sulfur fixation capacity of gangue minerals such as calcite and dolomite in iron ore has not been fully utilized. Under a reducing atmosphere, these minerals are difficult to effectively participate in sulfur fixation, resulting in serious sulfur emissions. Existing sulfur fixation technologies do not fix sulfur sufficiently, resulting in serious sulfur emissions. Relying on external sulfur fixation agents increases costs and the effect is unstable. Equipment corrosion problems are serious and maintenance costs are high. The sulfur fixation potential of calcite and dolomite has not been effectively utilized.
[0004] The present invention realizes in-situ sulfur fixation by utilizing calcite and dolomite naturally existing in iron ore in the pre-oxidation stage, reduces the use of external sulfur fixation agents, reduces sulfur emissions, improves environmental protection effects, alleviates equipment corrosion problems, and improves the roasting efficiency of iron ore. Summary of the invention
[0005] The high-sulfur iron ore produces SO during the reduction roasting process. 2 To solve the problem of polluting gases, the present invention provides an in-situ sulfur fixation device for pre-oxidation roasting of iron ore. By introducing a pre-oxidation roasting process before reduction roasting, pyrite and pyrrhotite in high-sulfur iron ore react with calcite and dolomite to remove SO 2 Converted into stable solid sulfide, thus effectively inhibiting SO 2 The generation of sulfur-fixing agent can be realized in situ, which reduces environmental pollution and does not require the introduction of additional sulfur-fixing agent.
[0006] To achieve the above object, the present invention adopts the following technical solutions:
[0007] An iron ore pre-oxidation roasting in-situ sulfur fixation device comprises a belt feeder, a storage bin, a weight loss scale, a screw feeder, a first preheating cyclone separator, a second preheating cyclone separator, a first flow sealing valve, a combustion station, a pre-oxidation suspension roasting furnace, a fluidized reduction roasting furnace, a first cyclone separator, a second cyclone separator, a first collection bin, a first heat exchanger, a bag dust collector, a second collection bin, a second heat exchanger, a Roots blower and a chimney;
[0008] The belt feeder, storage bin, loss-in-weight scale, and screw feeder are connected in sequence; the discharge port of the screw feeder is connected to the upper discharge port of the first preheating cyclone separator, and the upper discharge port of the first preheating cyclone separator, the second preheating cyclone separator, the first flow sealing valve, the preoxidation suspension roasting furnace, and the feed port of the first preheating cyclone separator are connected in sequence; the lower discharge port of the first preheating cyclone separator is connected to the fluidized reduction roasting furnace and the feed port of the second cyclone separator in sequence, and the upper discharge port of the second cyclone separator is connected to the bottom air inlet of the preoxidation suspension roasting furnace; the upper discharge port of the second preheating cyclone separator is connected to the feed port of the first cyclone separator, and the upper discharge port of the first cyclone separator is connected to the first heat exchanger, the bag-type dust collector, the second heat exchanger, and the chimney in sequence; a Roots blower is provided at the bottom of the second heat exchanger;
[0009] The pre-oxidation suspension roasting furnace is equipped with a combustion station, which is connected to a natural gas source through a pipeline;
[0010] The bottom of the fluidized reduction roasting furnace is provided with nitrogen and reducing gas inlets, wherein the reducing gas is H 2 and CO or a mixture of both;
[0011] The lower discharge port of the first cyclone separator is connected to the first material collection bin, and the lower discharge port of the bag-type dust collector is connected to the feed port of the second material collection bin;
[0012] The lower discharge port of the second cyclone separator is the discharge port of the final roasted product;
[0013] In the above device, a compressed air inlet is arranged at the bottom of the first flow sealing valve, and the compressed air inlet is connected to the air compressor.
[0014] In the above device, the combustion station is connected to the natural gas source through a pipeline.
[0015] In the above device, the reducing gas inlet is connected to the reducing gas source through a pipeline, and the nitrogen gas inlet is connected to the nitrogen gas source through a pipeline.
[0016] In the above device, the first heat exchanger and the second heat exchanger are tubular heat exchangers.
[0017] In the above device, temperature sensors are provided at the upper discharge port of the first preheating cyclone separator, the combustion station, the top of the pre-oxidation suspension roasting furnace, the inlet and discharge port of the fluidized reduction roasting furnace, the inlet and discharge port of the second cyclone separator, the inlet of the first heat exchanger, the inlet of the bag-type dust collector, the inlet of the second heat exchanger and the discharge port of the chimney.
[0018] In the above device, the system operates at negative pressure, and the Roots blower keeps the system in a negative pressure state.
[0019] In the above device, pressure sensors are provided at the upper and lower discharge ports of the first preheating cyclone separator, the lower discharge port of the second preheating cyclone separator, the top of the pre-oxidation suspension roasting furnace, the inlet of the first heat exchanger, the inlet of the bag-type dust collector, and the Roots blower.
[0020] In the above device, the gas valves used are all electromagnetic valves.
[0021] The method for using the iron ore pre-oxidation roasting in-situ sulfur fixation device is carried out according to the following steps:
[0022] (1) Using high-sulfur refractory iron ore with an iron grade of more than 20% and a sulfur content of more than 0.5% as raw material, the raw material is prepared by crushing and grinding to a particle size of less than 0.074 mm accounting for ≥ 70% of the total mass;
[0023] (2) The ground raw materials are fed into a storage bin via a belt feeder, and then transported to the discharge port of the first preheating cyclone separator via a loss-in-weight scale and a screw feeder;
[0024] (3) Starting the Roots blower to form a negative pressure in the system; the raw materials after grinding enter the second preheating cyclone separator for preheating, and after cyclone separation, the fine-grained raw materials enter the first cyclone separator, and the coarse-grained materials enter the first flow sealing valve, and compressed air is introduced into the first flow sealing valve to achieve material fluidization, and then enter the pre-oxidation suspension roasting furnace; the particle size <30 μm is the fine particle size, and the particle size ≥30 μm is the coarse particle size;
[0025] (4) The combustion station is turned on. The high-temperature flue gas generated by the combustion station is mixed with the preheated coarse-grained material in the pre-oxidation suspension roasting furnace. The coarse-grained material and the high-temperature flue gas are heated to 650°C to 1000°C to remove adsorbed water and crystallized water. The sulfide minerals in the coarse-grained material react with calcite and dolomite. The reaction products are mixed with the dehydration products to form high-temperature materials. Under the action of negative pressure, the high-temperature flue gas and the high-temperature materials are discharged from the top of the pre-oxidation suspension roasting furnace and enter the first preheating cyclone separator.
[0026] (5) The high-temperature material entering the first preheating cyclone separator is separated from the high-temperature flue gas, and the temperature of the high-temperature material and the gas is reduced to 500° C. to 800° C. to form a solid sulfur material. The solid sulfur material is separated, and the obtained fine-grained solid sulfur material is discharged from the upper discharge port along with the gas, and the coarse-grained solid sulfur material enters the fluidized reduction roasting furnace from the lower discharge port of the first preheating cyclone separator; wherein, the fine-grained solid sulfur material has a particle size of <30 μm, and the coarse-grained solid sulfur material has a particle size of ≥30 μm;
[0027] (6) Reducing gas and nitrogen are introduced into the fluidized reduction roasting furnace through the reducing gas inlet and the nitrogen inlet. The coarse-grained solid sulfur material is in a fluidized state under the action of the gas flow, and the temperature is reduced to 450° C. to 650° C. to react. The hematite therein is reduced to magnetite. After the reaction is completed, the solid material in the fluidized reduction roasting furnace is discharged from the upper discharge port of the fluidized reduction roasting furnace as a roasting product and enters the second cyclone separator;
[0028] (7) The roasted product is cooled to below 100° C. in the second cyclone separator and discharged from the lower discharge port of the second cyclone separator; the roasted product is subjected to chemical analysis to calculate the fixed sulfur rate, and then the iron ore concentrate is obtained by magnetic separation.
[0029] (8) The gas carrying fine-particle solid sulfur materials separated by the first preheating cyclone separator is further preheated and separated by the second preheating cyclone separator, and then enters the first cyclone separator to achieve gas-solid separation. The gas enters the first heat exchanger from the upper discharge port of the first cyclone separator for cooling, and the solid particles enter the first collection bin from the lower discharge port of the first cyclone separator; the cooled gas enters the bag-type dust collector for further dust removal, and the dust enters the second collection bin; the gas after further dust removal enters the second heat exchanger for further cooling, and is discharged into the atmosphere through the chimney.
[0030] In the above step (1), the sulfide mineral in the high-sulfur refractory iron ore is pyrite (FeS 2 ) and pyrrhotite (Fe 1-x S), the sum of calcite and dolomite content is greater than 5%.
[0031] In the above step (4), the main reactions that occur are as follows:
[0032] Pyrite oxidizes to form hematite and sulfur dioxide: 4FeS 2 +11O 2 →2Fe 2 O 3 +8SO 2
[0033] Pyrrhotite oxidizes to form hematite and sulfur dioxide: 2Fe 1-x S+(3.5-1.5x)O 2 →(1-x)Fe2 O 3 +2SO 2
[0034] Calcite decomposition reaction: CaCO 3 →CaO+CO 2
[0035] Dolomite decomposition reaction: CaMg(CO 3 ) 2 →CaO+MgO+2CO 2
[0036] Sulfur fixation reaction: 2SO 2 +2CaO+O 2 →2CaSO 4 ;2SO 2 +2MgO+O 2 →2MgSO 4
[0037] Siderite decomposition: 4FeCO 3 +3O 2 →2Fe 2 O 3 +4CO 2
[0038] Limonite Dehydration: mFe 2 O 3 ·nH 2 O=mFe 2 O 3 +nH 2 O
[0039] In the above step (4), the material stays in the pre-oxidation suspension roasting furnace for 1 min to 5 min.
[0040] In the above step (6), the reducing gas concentration in the fluidized reduction roasting furnace is 20% to 40%, and the coarse-grained sulfur-fixing material stays in the fluidized reduction roasting furnace for 10 minutes to 60 minutes.
[0041] In the above step (6), the reduction reaction of the iron mineral is:
[0042] 3Fe 2 O 3 +H 2 →2Fe 3 O 4 +H 2 O
[0043] 3Fe 2 O 3 +CO→2Fe 3 O 4+CO 2
[0044] In the above step (7), the sulfur fixation rate refers to the percentage of sulfur content formed as sulfate in the roasting process to the total sulfur content, and the sulfur fixation rate is ≥80%; the iron grade of the iron ore concentrate in the roasting product is 60% to 70%, and the iron recovery rate is 60% to 85%.
[0045] In the above step (7), during the cooling process of the roasted product in the cyclone separator, heat enters the pre-oxidation suspension roasting furnace from the upper discharge port of the second cyclone separator.
[0046] The key technology of the present invention is:
[0047] The present invention proposes an in-situ sulfur fixation device and method for pre-oxidation roasting of iron ore. The key point is to introduce pre-oxidation roasting before reduction roasting, and utilize the calcite (CaCO 3 ) and dolomite (CaMg(CO 3 ) 2 ) as an in-situ sulfur fixation agent. During the pre-oxidation roasting process, calcite and dolomite decompose to produce calcium oxide (CaO) and magnesium oxide (MgO). These oxides react with SO generated by the thermal decomposition of pyrite and pyrrhotite to form 2 reacts to form stable sulfate (CaSO 4 and MgSO 4 ), thereby effectively inhibiting SO 2 generation and reduce environmental pollution.
[0048] Compared with the prior art, the beneficial effects and innovations of the present invention are:
[0049] 1. Pre-oxidation roasting of high-sulfur iron ore before reduction roasting, using the naturally existing calcite and dolomite in the iron ore as sulfur-fixing agents to generate calcium oxide and magnesium oxide, which react with the SO generated by thermal decomposition of pyrite and pyrrhotite. 2 This method reduces the dependence on external sulfur fixation agents and reduces production costs.
[0050] 2. The pre-oxidation roasting process can convert siderite, pyrite and limonite into hematite, improving the uniformity of the roasted material. In addition, the gas escape generated during the pre-oxidation roasting process and the accompanying shrinkage and expansion of the structure increase the porosity of the roasted material, thereby improving the efficiency of the reduction reaction. BRIEF DESCRIPTION OF THE DRAWINGS
[0051] Figure 1 It is a schematic diagram of an in-situ sulfur fixation device for pre-oxidation roasting of iron ore in an embodiment of the present invention;
[0052] In the figure, 1. belt feeder, 2. storage bin, 3. loss-in-weight scale, 4. screw feeder, 5. first preheating cyclone separator, 6. second preheating cyclone separator, 7. first flow sealing valve, 8. combustion station, 9. pre-oxidation suspension roasting furnace, 10. fluidized reduction roasting furnace, 11. second cyclone separator, 12. first cyclone separator, 13. first collecting bin, 14. first heat exchanger, 15. bag-type dust collector, 16. second collecting bin, 17. second heat exchanger, 18. Roots blower, 19. chimney. DETAILED DESCRIPTION
[0053] The belt feeder, storage bin, loss-in-weight scale, screw feeder, combustion station, collection bin, heat exchanger, bag-type dust collector, Roots blower and chimney used in the embodiments of the present invention are commercially available products.
[0054] The first preheating cyclone separator, the second preheating cyclone separator, the first cyclone separator, and the second cyclone separator used in the embodiment of the present invention are all commercially available cyclone separators.
[0055] The high-sulfur refractory iron ore used in the embodiment of the present invention has an iron grade greater than 20%, a sulfur content greater than 0.5%, and a calcite and dolomite content greater than 5%.
[0056] Example 1
[0057] The iron ore pre-oxidation roasting in-situ sulfur fixation device of the present invention is as follows Figure 1As shown, it includes a belt feeder 1, a storage bin 2, a weight loss scale 3, a screw feeder 4, a first preheating cyclone separator 5, a second preheating cyclone separator 6, a first flow sealing valve 7, a combustion station 8, a pre-oxidation suspension roasting furnace 9, a fluidized reduction roasting furnace 10, a second cyclone separator 11, a first cyclone separator 12, a first collection bin 13, a first heat exchanger 14, a bag dust collector 15, a second collection bin 16, a second heat exchanger 17, and a Roots blower 1 8 and chimney 19; the discharge port of the feeder 1 cooperates with the feed port of the storage bin 2, the material in the storage bin 2 is fed into the screw feeder 4 through the loss-in-weight scale 3, the discharge port of the screw feeder 4 is connected to the upper discharge port of the first preheating cyclone separator 5, the upper discharge port of the first preheating cyclone separator 5 is connected to the feed port of the second preheating cyclone separator 6, the material and the fine-grained material and hot air in the upper discharge port of the first preheating cyclone separator 5 enter the second preheating cyclone separator 6, the lower discharge port of the second preheating cyclone separator 6 is connected to the feed port of the first flow sealing valve 7, the upper discharge port of the second preheating cyclone separator 6 is connected to the feed port of the first cyclone separator 12, the discharge port of the first flow sealing valve 7 is connected to the feed port of the lower part of the preoxidation suspension roasting furnace 9, the preoxidation suspension roasting furnace 9 is equipped with a combustion station 8, and the upper discharge port of the preoxidation suspension roasting furnace 9 is connected to the feed port of the first preheating cyclone separator 5, The lower discharge port of the first preheating cyclone separator 5 is connected to the feed port at the top of the fluidized reduction roasting furnace 10. A nitrogen inlet and a reducing gas inlet are provided at the bottom of the fluidized reduction roasting furnace 10. The discharge port at the top of the fluidized reduction roasting furnace 10 is connected to the feed port of the second cyclone separator 11. The upper discharge port of the second cyclone separator 11 is connected to the air inlet at the bottom of the pre-oxidation suspension roasting furnace 9. The lower discharge port of the second cyclone separator 11 is the discharge port of the final roasting product. The lower discharge port of the first cyclone separator 12 is connected to the first collecting bin 13, the upper discharge port of the first cyclone separator 12 is connected to the feed port of the first heat exchanger 14, the discharge port of the first heat exchanger 14 is connected to the feed port of the bag-type dust collector 15, the lower discharge port of the bag-type dust collector 15 is connected to the feed port of the second collecting bin 16, the upper discharge port of the bag-type dust collector 15 is connected to the feed port of the second heat exchanger 17, the discharge port of the second heat exchanger 17 is connected to the chimney 19, and the bottom of the second heat exchanger 17 is equipped with a Roots blower 18 to provide negative pressure power for the system.
[0058] The above device is used to carry out in-situ sulfur fixation of iron ore pre-oxidation roasting, and the method is as follows:
[0059] The iron grade of high-sulfur refractory iron ore is 28.79%, the sulfur content is 2.38%, the calcite content is 3.89%, and the dolomite content is 2.67%. The raw ore is crushed and ground to -0.074mm, accounting for 70%.
[0060] The ground raw materials are fed into the storage bin 2 through the belt feeder 1 , and then transported to the discharge port of the first preheating cyclone separator 5 through the loss-in-weight scale 3 and the screw feeder 4 .
[0061] During the operation of the system, the Roots blower 18 needs to be started to form a negative pressure in the system. The raw materials after grinding enter the second preheating cyclone separator 6 for preheating. After cyclone separation, the fine-grained raw materials (particle size <30μm) enter the first cyclone separator, and the coarse-grained materials (particle size ≥30μm) enter the first flow sealing valve 7. Compressed air is introduced into the first flow sealing valve 7 to achieve material fluidization, and then the fluidized materials enter the pre-oxidation suspension roasting furnace 9.
[0062] The combustion station 8 is turned on. The high-temperature flue gas generated by the combustion station 8 is mixed with the preheated coarse-grained material in the pre-oxidation suspension roasting furnace 9. The coarse-grained material is heated to 1000°C and stays for 1 minute to remove adsorbed water and part of the crystal water. The sulfide minerals in the material (mainly pyrite and pyrrhotite) react with calcite and dolomite to form stable sulfate (CaSO 4 and MgSO 4 ) to achieve sulfur fixation, the solid part formed by the reaction is high-temperature material, and the gas part formed is water vapor. Under the action of negative pressure, the high-temperature material and high-temperature gas are discharged from the top of the pre-oxidation suspension roasting furnace 9 and enter the first preheating cyclone separator 5.
[0063] The high-temperature material entering the first preheating cyclone separator 5 is separated from the water vapor, and the temperature is reduced to 800°C to form a solid sulfur material. The solid sulfur material is separated, and the coarse-grained solid sulfur material (particle size ≥ 30μm) obtained enters the fluidized reduction roasting furnace 10 from the discharge port of the first preheating cyclone separator 5, and the fine-grained solid sulfur material (particle size <30μm) is discharged from the upper discharge port of the first preheating cyclone separator 5 along with the water vapor.
[0064] Reducing gas and nitrogen are introduced into the fluidized reduction roasting furnace 10 through the reducing gas inlet and the nitrogen inlet, so that the coarse-grained materials in the fluidized reduction roasting furnace 10 are in a fluidized state under the action of the airflow and the temperature is reduced to 650°C. The residence time of the coarse-grained materials is 10 minutes. The reducing gas is H 2 The hematite in the material is reduced to magnetite. After the reaction is completed, the solid material in the fluidized reduction roasting furnace 10 is discharged from the upper discharge port of the fluidized reduction roasting furnace 10 as a roasting product and enters the second cyclone separator 11.
[0065] The roasted product is cooled to 90°C by the second cyclone separator 11 and discharged from the lower discharge port of the second cyclone separator 11, and the heat enters the pre-oxidation suspension roasting furnace from the upper discharge port of the second cyclone separator 11. According to the analysis, the solid sulfur rate is 85.37%, and the iron concentrate is obtained by magnetic separation after the roasted product, with an iron grade of 60.32% and an iron recovery rate of 83.21%.
[0066] The water vapor separated by the first preheating cyclone separator 5 carries the fine-grained solid sulfur material as tail gas and enters the first cyclone separator 12 from the upper discharge port of the first preheating cyclone separator 5 through the second preheating cyclone separator 6 to achieve gas-solid separation. The gas enters the first heat exchanger 14 from the upper discharge port of the first cyclone separator 12 for cooling, and the solid particles enter the first collection bin 13 from the lower discharge port of the first cyclone separator 12; the cooled gas enters the bag-type dust collector 15 for further dust removal, and the dust enters the second collection bin 16; the gas after further dust removal enters the second heat exchanger 17 for further cooling and is discharged into the atmosphere through the chimney 19.
[0067] Example 2
[0068] The device structure is the same as that of Example 1;
[0069] The method is the same as in Example 1, except that:
[0070] The iron grade of high-sulfur refractory iron ore is 35.42%, the sulfur content is 1.87%, the calcite content is 4.32%, and the dolomite content is 1.56%. The raw ore is crushed and ground to -0.074mm, accounting for 75%.
[0071] The material is heated to 900°C in the pre-oxidation suspension roasting furnace 9 with a residence time of 2 minutes; cooled to 650°C in the first preheating cyclone separator 5, and cooled to 600°C in the fluidized reduction roasting furnace 10. The reducing gas is CO with a concentration of 30% and a residence time of 20 minutes.
[0072] The roasted product is cooled to 80° C. by the second cyclone separator 11, and the sulfur fixation rate is 82.13%. After the roasted product is roasted, iron concentrate is obtained by magnetic separation, and the iron grade is 66.17%, and the iron recovery rate is 79.36%.
[0073] Example 3
[0074] The device structure is the same as that of Example 1;
[0075] The method is the same as in Example 1, except that:
[0076] The iron grade of high-sulfur refractory iron ore is 32.16%, the sulfur content is 0.98%, the calcite content is 2.19%, and the dolomite content is 3.52%. 80% of the raw ore is crushed and ground to -0.074mm.
[0077] The material is heated to 800°C in the pre-oxidation suspension roasting furnace 9 with a residence time of 2.5 min; cooled to 550°C in the first preheating cyclone separator 5, and cooled to 550°C in the fluidized reduction roasting furnace 10. The reducing gas is CO and H 2 (ratio 1:3), concentration is 40%, and residence time is 30min.
[0078] The roasted product is cooled to 80° C. by the second cyclone separator 11, and the sulfur fixation rate is 89.30%. After the roasted product is roasted, iron concentrate is obtained by magnetic separation, with an iron grade of 64.37% and an iron recovery rate of 76.25%.
[0079] Example 4
[0080] The device structure is the same as that of Example 1;
[0081] The method is the same as in Example 1, except that:
[0082] The iron grade of high-sulfur refractory iron ore is 23.56%, the sulfur content is 2.96%, the calcite content is 2.69%, and the dolomite content is 4.56%. 80% of the raw ore is crushed and ground to -0.074mm.
[0083] The material is heated to 650°C in the pre-oxidation suspension roasting furnace 9 with a residence time of 5 min; cooled to 500°C in the first preheating cyclone separator 5, and cooled to 450°C in the fluidized reduction roasting furnace 10 with the reducing gas being H 2 , concentration is 20%, and residence time is 60min.
[0084] The roasted product is cooled to 80° C. by the second cyclone separator 11, and the sulfur fixation rate is 86.78%. After the roasted product is roasted, iron concentrate is obtained by magnetic separation, and the iron grade is 62.18%, and the iron recovery rate is 80.15%.
[0085] Example 5
[0086] The device structure is the same as that of Example 1;
[0087] The method is the same as in Example 1, except that:
[0088] The iron grade of high-sulfur refractory iron ore is 29.58%, the sulfur content is 1.45%, the calcite content is 3.35%, and the dolomite content is 3.89%. The raw ore is crushed and ground to -0.074mm, accounting for 85%.
[0089] The material is heated to 750°C in the pre-oxidation suspension roasting furnace 9 with a residence time of 3 minutes; cooled to 600°C in the first preheating cyclone separator 5, and cooled to 550°C in the fluidized reduction roasting furnace 10. The reducing gas is CO with a concentration of 30% and a residence time of 50 minutes.
[0090] The roasted product is cooled to 90° C. by the second cyclone separator 11, and the sulfur fixation rate is 91.02%. After the roasted product is obtained, iron concentrate is obtained by magnetic separation, and the iron grade is 66.58%, and the iron recovery rate is 70.32%.
[0091] Example 6
[0092] The device structure is the same as that of Example 1;
[0093] The method is the same as in Example 1, except that:
[0094] The iron grade of high-sulfur refractory iron ore is 35.69%, the sulfur content is 1.28%, the calcite content is 2.98%, and the dolomite content is 2.59%. 80% of the raw ore is crushed and ground to -0.074mm.
[0095] The material is heated to 800°C in the pre-oxidation suspension roasting furnace 9 with a residence time of 2 min; cooled to 650°C in the first preheating cyclone separator 5, and cooled to 600°C in the fluidized reduction roasting furnace 10. The reducing gas is CO and H 2 (ratio 2:1), concentration is 35%, and residence time is 30min.
[0096] The roasted product is cooled to 80° C. by the second cyclone separator 11, and the sulfur fixation rate is 83.56%. After the roasted product is roasted, iron concentrate is obtained by magnetic separation, and the iron grade is 67.89%, and the iron recovery rate is 74.69%.
Claims
1. An iron ore pre-oxidation roasting in-situ sulfur fixation device, characterized in that: It includes a belt feeder, a storage bin, a loss-in-weight scale, a screw feeder, a first preheating cyclone separator, a second preheating cyclone separator, a first flow sealing valve, a combustion station, a pre-oxidation suspension roasting furnace, a fluidized reduction roasting furnace, a first cyclone separator, a second cyclone separator, a first collecting bin, a first heat exchanger, a bag dust collector, a second collecting bin, a second heat exchanger, a Roots blower and a chimney; The belt feeder, storage bin, loss-in-weight scale and screw feeder are connected in sequence; The discharge port of the spiral feeder is connected to the upper discharge port of the first preheating cyclone separator, and the upper discharge port of the first preheating cyclone separator, the second preheating cyclone separator, the first flow sealing valve, the pre-oxidation suspension roasting furnace, and the feed port of the first preheating cyclone separator are connected in sequence; The lower discharge port of the first preheating cyclone separator is connected to the fluidized reduction roasting furnace and the feed port of the second cyclone separator in sequence, and the upper discharge port of the second cyclone separator is connected to the bottom air inlet of the pre-oxidation suspension roasting furnace; the upper discharge port of the second preheating cyclone separator is connected to the feed port of the first cyclone separator, and the upper discharge port of the first cyclone separator is connected to the first heat exchanger, the bag-type dust collector, the second heat exchanger, and the chimney in sequence; a Roots blower is provided at the bottom of the second heat exchanger.
2. The device for in-situ sulfur fixation of iron ore pre-oxidation roasting according to claim 1, characterized in that: The belt feeder, storage bin, loss-in-weight scale, and screw feeder are connected in sequence; the discharge port of the screw feeder is connected to the upper discharge port of the first preheating cyclone separator, and the upper discharge port of the first preheating cyclone separator, the second preheating cyclone separator, the first flow sealing valve, the pre-oxidation suspension roasting furnace, and the feed port of the first preheating cyclone separator are connected in sequence; the lower discharge port of the first preheating cyclone separator is connected to the fluidized reduction roasting furnace and the feed port of the second cyclone separator in sequence, and the upper discharge port of the second cyclone separator is connected to the bottom air inlet of the pre-oxidation suspension roasting furnace; the upper discharge port of the second preheating cyclone separator is connected to the feed port of the first cyclone separator, and the upper discharge port of the first cyclone separator is connected to the first heat exchanger, the bag-type dust collector, the second heat exchanger, and the chimney in sequence; a Roots blower is provided at the bottom of the second heat exchanger.
3. The device for in-situ sulfur fixation of iron ore pre-oxidation roasting according to claim 1, characterized in that: The pre-oxidation suspension roasting furnace is equipped with a combustion station, which is connected to a natural gas source through a pipeline; The lower discharge port of the first cyclone separator is connected to the first material collection bin, and the lower discharge port of the bag-type dust collector is connected to the feed port of the second material collection bin; The bottom of the fluidized reduction roasting furnace is provided with nitrogen and reducing gas inlets.
4. The device for in-situ sulfur fixation of iron ore pre-oxidation roasting according to claim 1, characterized in that: The combustion station is connected to the natural gas source through a pipeline; The lower discharge port of the second cyclone separator is the discharge port of the final roasted product; A compressed air inlet is provided at the bottom of the first flow sealing valve, and the compressed air inlet is connected to the air compressor; The reducing gas inlet is connected to the reducing gas source through a pipeline, and the nitrogen gas inlet is connected to the nitrogen gas source through a pipeline; The first heat exchanger and the second heat exchanger are tubular heat exchangers.
5. The device for in-situ sulfur fixation of iron ore pre-oxidation roasting according to claim 1, characterized in that: Temperature sensors are provided at the upper discharge port of the first preheating cyclone separator, the combustion station, the top of the pre-oxidation suspension roasting furnace, the feed inlet and discharge port of the fluidized reduction roasting furnace, the feed inlet and discharge port of the second cyclone separator, the feed inlet of the first heat exchanger, the feed inlet of the bag-type dust collector, the feed inlet of the second heat exchanger and the discharge port of the chimney; Pressure sensors are provided at the upper and lower discharge ports of the first preheating cyclone separator, the lower discharge port of the second preheating cyclone separator, the top of the pre-oxidation suspension roasting furnace, the inlet of the first heat exchanger, the inlet of the bag-type dust collector, and the Roots blower.
6. A method for using the iron ore pre-oxidation roasting in-situ sulfur fixation device according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step 1. Use high-sulfur refractory iron ore as raw material, and crush and grind the raw material; Step 2. Feed the ground raw materials into a storage bin through a belt feeder, and then transport them to the discharge port of the first preheating cyclone separator through a loss-in-weight scale and a screw feeder; Step 3. Start the Roots blower to form a negative pressure in the system; the raw materials after grinding enter the second preheating cyclone separator for preheating, and after cyclone separation, the fine-grained raw materials enter the first cyclone separator, and the coarse-grained materials enter the first flow sealing valve. Compressed air is introduced into the first flow sealing valve to achieve material fluidization, and then enter the pre-oxidation suspension roasting furnace; Step 4. Turn on the combustion station, and the high-temperature flue gas generated by the combustion station is mixed with the preheated coarse-grained material in the pre-oxidation suspension roasting furnace. The coarse-grained material and the high-temperature flue gas are heated to 650°C to 1000°C to react, and the product forms a high-temperature material; under the action of negative pressure, the high-temperature flue gas and the high-temperature material are discharged from the top of the pre-oxidation suspension roasting furnace and enter the first preheating cyclone separator; Step 5. The high-temperature material entering the first preheating cyclone separator is separated from the high-temperature flue gas, and the temperature of the high-temperature material and the gas is reduced to 500° C. to 800° C. to form a solid sulfur material. The solid sulfur material is separated, and the obtained fine-grained solid sulfur material is discharged from the upper discharge port along with the gas, and the coarse-grained solid sulfur material enters the fluidized reduction roasting furnace from the lower discharge port of the first preheating cyclone separator; Step 6. Reducing gas and nitrogen are introduced into the fluidized reduction roasting furnace through the reducing gas inlet and the nitrogen inlet. The coarse-grained solid sulfur material is in a fluidized state under the action of the gas flow, and the temperature is reduced to 450° C. to 650° C. to react. After the reaction is completed, the solid material in the fluidized reduction roasting furnace is discharged from the upper discharge port of the fluidized reduction roasting furnace as a roasting product and enters the second cyclone separator; Step 7. The roasted product is cooled to below 100° C. in the second cyclone separator and discharged from the lower discharge port of the second cyclone separator, and the heat enters the pre-oxidation suspension roasting furnace from the upper discharge port of the second cyclone separator; the roasted product is analyzed and the fixed sulfur rate is calculated, and then the iron concentrate is obtained by magnetic separation; Step 8. The gas carrying fine-grained solid sulfur materials separated by the first preheating cyclone separator is further preheated and separated by the second preheating cyclone separator, and then enters the first cyclone separator to achieve gas-solid separation. The gas enters the first heat exchanger from the upper discharge port of the first cyclone separator for cooling, and the solid particles enter the first collection bin from the lower discharge port of the first cyclone separator; the cooled gas enters the bag filter for further dust removal, and the dust enters the second collection bin; the gas after further dust removal enters the second heat exchanger for further cooling and is discharged into the atmosphere through the chimney; The particle sizes of the fine-grained material and the fine-grained sulfur-fixing material are both <30 μm, and the particle sizes of the coarse-grained material and the coarse-grained sulfur-fixing material are both ≥30 μm.
7. The method for using the device for in-situ sulfur fixation of iron ore pre-oxidation roasting according to claim 6 is characterized in that: In step 1, the high-sulfur refractory ore has an iron grade of >20% and a sulfur content of >0.5%; the sulfides in the high-sulfur refractory ore are pyrite and pyrrhotite, and the sum of the calcite and dolomite contents is >5%; The part of the raw material with a particle size less than 0.074 mm after grinding accounts for ≥70% of the total mass.
8. The method for using the device for in-situ sulfur fixation of iron ore pre-oxidation roasting according to claim 7, characterized in that: In step 4, the coarse-grained material removes adsorbed water and crystallized water, and the sulfide minerals in the coarse-grained material react with calcite and dolomite; wherein pyrite is oxidized to generate hematite and sulfur dioxide, and pyrrhotite is oxidized to generate hematite and sulfur dioxide; The coarse-grained material stays in the pre-oxidation suspension roasting furnace for 1 to 5 minutes.
9. The method for using the device for in-situ sulfur fixation of iron ore pre-oxidation roasting according to claim 8, characterized in that: In step 6, the reducing gas concentration in the fluidized reduction roasting furnace is 20% to 40%, and the coarse-grained sulfur-fixing material stays in the fluidized reduction roasting furnace for 10 minutes to 60 minutes; The reducing gas is one of H2 and CO or a mixture of the two; Hematite is reduced to magnetite.
10. The method for using the device for in-situ sulfur fixation of iron ore pre-oxidation roasting according to claim 6, characterized in that: In step 7, the sulfur fixation rate is ≥80%; the iron grade of the iron ore concentrate in the roasting product is 60% to 70%, and the iron recovery rate is 60% to 85%.