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CN-121992157-A - Method for thermal state circulation treatment of steel slag

CN121992157ACN 121992157 ACN121992157 ACN 121992157ACN-121992157-A

Abstract

The invention discloses a method for thermal state circulation treatment of steel slag, which is based on the characteristics of steel slag and solid waste of a steel mill, and provides a new idea of carrying out coordinated treatment on the steel slag and specific solid waste so as to realize the synergistic absorption of the solid waste by dephosphorization of the steel slag. Compared with the existing reduction gasification dephosphorization technology, the dephosphorization effect is better, the exhaust emission is small, no wastewater is discharged, and the technology is simpler, the stability is stronger, and the investment cost is lower.

Inventors

  • YANG BENTAO
  • GAO XU
  • YUE WENYI
  • CHEN HONG
  • XUE NING
  • LI YONG
  • NING JIANGBO
  • ZHOU YOU

Assignees

  • 湖南中冶长天节能环保技术有限公司
  • 中南大学

Dates

Publication Date
20260508
Application Date
20241101

Claims (10)

  1. 1. A method for thermal state circulation treatment of steel slag is characterized by comprising the following steps: 1) Adding multi-source solid wastes into hot steel slag discharged from a converter to react, and obtaining a mixed solid solution after the reaction is completed; 2) Collecting the upper layer material of the mixed solid solution and circulating the upper layer material as converter furnace charge, collecting the middle layer material of the mixed solid solution and circulating the middle layer material as sintering material, collecting the lower layer material of the mixed solid solution and adding the lower layer material into thermal steel slag for circulation in step 1).
  2. 2. The method according to claim 1, wherein in the step 1), the multi-source solid waste is mixed solid waste composed of coal gangue, waste carbon powder, blast furnace bag dust, aluminum dust, sintering dust and converter secondary dust.
  3. 3. The method according to claim 1 or 2, wherein the multi-source solid waste comprises 10-40wt% of coal gangue, 5-30wt% of waste carbon powder, 5-25wt% of blast furnace bag ash, 15-40wt% of aluminum ash, 3-15wt% of sintered ash, 2-15wt% of converter secondary ash, preferably 15-30wt% of coal gangue, 10-25wt% of waste carbon powder, 10-20wt% of blast furnace bag ash, 20-35wt% of aluminum ash, 5-12wt% of sintered ash and 5-12wt% of converter secondary ash.
  4. 4. The method according to any one of claims 1 to 3, wherein the amount of the multi-source solid waste is 5 to 20%, preferably 5 to 18%, more preferably 7 to 15% of the total mass of the hot steel slag.
  5. 5. The method according to any one of claims 1 to 4, wherein the temperature of the hot steel slag is 1400 to 1700 ℃, preferably 1450 to 1650 ℃, more preferably 1500 to 1600 ℃.
  6. 6. The method according to any one of claims 1 to 5, wherein in step 1), the reaction is a stirred reaction for a period of 0.2 to 2 hours, preferably 0.3 to 1.5 hours, more preferably 0.4 to 1 hour.
  7. 7. The method according to any one of claims 1 to 6, wherein in step 2), the upper layer material accounts for 60 to 85%, preferably 65 to 80%, more preferably 70 to 75% of the total mass of the mixed solid solution; Preferably, the phosphorus content in the upper layer material is not higher than 0.5%, preferably not higher than 0.3%, more preferably not higher than 0.2%.
  8. 8. The method according to any one of claims 1 to 7, wherein in step 2), the middle layer material accounts for 3 to 25%, preferably 5 to 20%, more preferably 10 to 15% of the total mass of the mixed solid solution; preferably, the mass content of chlorine in the middle layer material is not less than 0.3%, preferably not less than 0.5%, more preferably not less than 0.7%.
  9. 9. The method according to any one of claims 1 to 8, wherein in step 3), the lower layer material accounts for 1 to 20%, preferably 3 to 18%, more preferably 5 to 15% of the total mass of the mixed solid solution; preferably, the lower layer material is circularly processed in the step 1) for a plurality of times (for example, 3-8 times) and then discharged.
  10. 10. The method according to any of claims 1 to 9, characterized in that in step 1) the gas produced is filtered with a ceramic membrane (preferably under negative pressure) and discharged, and the dust obtained by the filtration is returned to the sinter batch.

Description

Method for thermal state circulation treatment of steel slag Technical Field The invention relates to steel slag treatment, in particular to a method for thermal state circulation treatment of steel slag, and belongs to the technical field of steel slag and solid waste comprehensive treatment. Background The steel slag discharge amount in China is huge, the annual newly increased discharge amount exceeds 1 hundred million tons, and at present, the steel slag treatment mainly takes cement building materials as main materials, and the problems of low added value, low utilization rate (only about 40%) and the like exist. With the amendment of GB175-2023 general Portland Cement, it is explicitly stated that by the time of day 1 of 6.2024, steel slag can no longer be used as a mixed material for general Portland cement. Proper treatment of steel slag becomes a serious bottleneck problem of green sustainable development in the steel industry in China. The steel slag is rich in a large amount of iron resources, and the iron oxide reaches 15-25%, but the steel slag contains a large amount of harmful elements (phosphorus) of steel materials, so that the space for recycling the steel slag is limited. If the dephosphorization technology of the steel slag can be developed, the restriction of internal circulation smelting of the steel slag is broken through, the steel slag discharge can be greatly reduced, the production of building materials is not needed, and the source reduction and the resource circulation are realized. Aiming at the steel slag dephosphorization technology, chinese patent CN117778669A discloses a method for gasifying and dephosphorizing converter final slag and recycling dephosphorization slag, wherein a carbonaceous dephosphorization agent is added into the converter slag for gasifying and dephosphorizing, and the dephosphorization slag can be recycled to a sintering process. The method can effectively remove phosphorus and realize the circulation of steel slag, but has the problems of poor dephosphorization effect, poor slag-phosphorus separation effect and the like in practical application. Chinese patent CN110184399a discloses a "steel slag treatment method using two steps of oxidative desulfurization and reductive dephosphorization", wherein dephosphorization adopts gas-based reductive dephosphorization, and uses mixed gas of CO and CO 2 to convert phosphorus into phosphorus gas for removal, and the dephosphorization effect of the method is good and can reach 80%, but the method has high toxicity of phosphorus gas, and risk of personnel poisoning and explosion of mixed gas exists. Chinese patent CN110526745A discloses a method for separating phosphorus from dephosphorized steel slag and preparing phosphate fertilizer, firstly, oxidizing the dephosphorized steel slag in a molten state, cooling, crushing and leaching to obtain low-phosphorus residues and phosphorus-containing leaching solution, wherein the method can effectively remove and recycle phosphorus to a certain extent, but the steel slag amount is large, the produced byproduct waste water amount is too large, and the disposal cost is high. Disclosure of Invention Aiming at the problems of poor dephosphorization effect, large exhaust emission, large wastewater emission and the like in the prior art of steel slag treatment, the invention provides a method for thermal state circulation treatment of steel slag, which is characterized in that thermal state steel slag and multi-source solid waste are mixed for reaction, so that solid solution state and layered phosphorus-free slag, high chlorine slag and ferrophosphorus slag can be obtained, and then the solid solution state and layered phosphorus slag, high chlorine slag and ferrophosphorus slag can be respectively circulated to corresponding procedures of steel production for digestion. In order to achieve the technical purpose, the technical scheme adopted by the invention is as follows: A method for thermal state recycling of steel slag, the method comprising: 1) Adding multi-source solid wastes into hot steel slag discharged from a converter to react, and obtaining a mixed solid solution after the reaction is completed. 2) Collecting the upper layer material of the mixed solid solution and circulating the upper layer material as converter furnace charge, collecting the middle layer material of the mixed solid solution and circulating the middle layer material as sintering material, collecting the lower layer material of the mixed solid solution and adding the lower layer material into thermal steel slag for circulation in step 1). Preferably, in the step 1), the multi-source solid waste is mixed solid waste composed of coal gangue, waste carbon powder, blast furnace cloth bag ash, aluminum ash, sintering ash and converter secondary ash. Preferably, the multi-source solid waste comprises 10-40wt% of coal gangue, 5-30wt% of waste carbon powder, 5-25wt% of blast furnace cloth bag ash, 15-40