Method for treating illite steel slag in short process

Abstract

The invention discloses a method for treating illite steel slag in a short process, and relates to a silicate phase change technology, a roasting magnetization technology and an on-line hardening and tempering technology of steel slag. According to the invention, a modification technology and a silicate phase change technology of liquid steel slag are utilized, fly ash and coal slime generated by an illite Rayleigh coking plant are added into the high-alkalinity converter steel slag, the alkalinity of the steel slag is adjusted, and a wear-resistant phase in the high-alkalinity steel slag is reduced, so that the steel slag can be fragmented without a hot disintegration process; and iron-containing minerals and silicate minerals in the steel slag can be easily separated, so that the efficiency of recovering iron-containing materials from the steel slag is improved, the energy consumption of steel slag crushing and magnetic separation procedures is saved, the technological process of traditional steel slag hot disintegration is shortened, the resource utilization performance of the steel slag is optimized, and the strength of technical innovation is manifested.

Description

Technical Field

[0001] The invention relates to a method for treating Yigang steel slag in a short process, and belongs to the technical fields of silicate phase change technology, roasting magnetization technology and online quenching and tempering of steel slag. Background Art

[0002] Yili Steel is located in Zeketai Town, Xinyuan County, and is a pillar enterprise in the Yili region. The converter slag produced by Yili Steel's steelmaking production line began to adopt the traditional hot slag treatment process in 2024. During the hot smoldering process of the slag, the slag often clumps. The process before covering the hot smoldering requires excavators to dig, stir the slag and spray water for treatment many times, and the hot smoldering time is long. After the hot smoldering, the slag requires multi-stage crushing and screening treatment, and the process cost is high. In addition, the f-MgO and f-CaO in the slag fluctuate greatly, affecting the resource utilization of the slag. The above phenomenon not only occurs in Yili Steel, but is also a common problem in the domestic steel industry, and there has been no effective solution process.

[0003] Literature review (1) Liang Jun published a paper titled “Analysis of the Explosion Mechanism and Control Measures in the Hot Smelting Slag Process” in the 4th issue of Industrial Heating in 2013. The paper states that “In the hot smelting slag process of a steel plant, explosions caused by gas were frequent, which restricted the safe production. For this reason, the Safety Supervision Department organized technical personnel from steelmaking, slag treatment, water supply and drainage, and ventilation to carry out technical demonstration and research”; (2) Chai Yifan, Peng Jun, and An Shengli published a paper titled “Overview of Comprehensive Utilization of Steel Slag and Hot Smelting Technology of Steel Slag” in the 3rd issue of Journal of Inner Mongolia University of Science and Technology in 2012. The paper states that “In the hot smelting process of steel slag, the pulverization effect of steel slag is unstable, and the hot smelting process is prone to explosion. This is also a problem that currently plagues domestic steel plants in the hot smelting method of steel slag treatment. Therefore, the transformation of the hot smelting device of steel slag is also an important problem that needs to be solved in the development of hot slag technology.” According to the above statements, it can be seen that the industry currently has no introduction to effective innovative technologies for the transformation of pit-type (slag pool) hot smelting process.

[0004] The results of the inventor's analysis of the adherends show that the RO phase (continuous solid solution) coexists with a small amount of incompletely precipitated calcium ferrite in the large block of steel slag, and is distributed between the calcium silicon phase and f-CaO in a continuous and extended state. Based on this analysis, the inventor found that "the large block of steel slag is due to the high content of metallic iron in the steel slag. The ferrite in the steel slag is a bonding phase that binds other minerals and adheres to the metallic iron (steel block) to form a stable mineral, which makes it difficult to peel off the metallic iron during the hot stuffing process." This is the main factor affecting the water-stoking effect in the hot stuffing process. At the same time, due to the presence of the ferrite phase, after the hot converter steel slag is poured into the hot stuffing slag pool, the hot steel slag is solidified and stirred by an excavator to form multiple solidified slag blocks. However, the growth of the low-melting-point calcium ferrite mineral phase can still bond the stirred slag blocks together to form secondary solidification agglomerates of the steel slag, causing the water added to the hot stuffing slag pool during the hot stuffing process of the steel slag to be unable to easily penetrate the agglomerate part, affecting the hot stuffing effect of the steel slag. Summary of the invention

[0005] The object of the present invention is to provide a method for processing Yigang steel slag in a short process. By utilizing liquid steel slag modification technology and silicate phase change technology, fly ash and coal slime produced by Yigang Ruixiang Coking Plant are added to high-alkalinity converter steel slag, the alkalinity of the steel slag is adjusted, and the wear-resistant phase in the high-alkalinity steel slag is reduced, so that the steel slag can be crushed without a hot stuffing process, and the iron-containing minerals and silicate minerals in the steel slag can be easily separated, thereby improving the efficiency of recovering iron-containing materials from the steel slag, saving energy consumption in the processes of steel slag crushing and magnetic separation, shortening the process flow of traditional steel slag hot stuffing, and optimizing the resource utilization performance of steel slag.

[0006] The process content of the present invention is as follows: A method for treating Yigang steel slag in a short process is implemented according to the following steps: 1) The fly ash and coal sludge (carbon content of 33% to 35%) produced by Yigang Ruixiang Coking Plant are mixed evenly in a mass percentage of 30%:70%, and then produced into pellets with a particle size of 10 to 20 mm using a high-pressure dry powder briquetting machine; the above pellets are transported to the hot slag pool for use; 2) At the beginning of the slag treatment process, a layer of hot steel slag is first poured into the bottom of the hot slag pool, and the above pellets are added to the top of the steel slag. The amount added is 300-500kg per ton of steel slag; 3) After adding the pellets, continue to pour liquid steel slag on the top of the pellets. After pouring the liquid steel slag, there is no need to use an excavator to stir it. Wait for the liquid steel slag to solidify and continue to add the above pellets to the slag surface; 4) Repeat the above operation until the slag pool is filled with steel slag; 5) After the slag pool is filled with steel slag, slowly cool it for 4 hours, and then spray water into the slag pool to cool it; 6) The slag pool does not need to be covered or kept hot. It only needs to be cooled to about 100°C by pumping water. Then the slag is dug out by an excavator and directly put into the slag screening and magnetic separation process. The iron-containing materials separated by the magnetic separation are returned to the steel plant for recycling, and the tailings are directly utilized as raw materials for road projects, cement production, and building materials.

[0007] The inventors have designed a method for tempering converter slag by utilizing the thermodynamic and kinetic conditions of high-temperature converter slag and adding reducing materials and active materials in the slag treatment process.

[0008] According to the on-site tempering test conducted by the inventor, the tempered steel slag is easy to separate from the (steel blocks) in the steel slag, but the smoke and combustion generated by the reaction pose a safety hazard to the on-site operations. We have made corresponding improvements, namely, the improvement technology of reducing agents and active materials to solve the safety problem. At the same time, considering the need to simultaneously solve the hidden dangers of f-MgO and f-CaO in the steel slag, we selected the waste coal slime (fixed carbon at 33% to 35%) and fly ash (the mass percentage content of Al2O3+SiO2 is greater than 85%, and the fixed carbon content is greater than 100%). The mass percentage of carbon is 3.5% to 5.8%) as a slow-release reducing agent, and good results have been achieved. It solves the problem that the steel blocks in the steel slag are difficult to separate from the steel slag after the steel slag is poured into the hot slag pool. At the same time, it solves the problem of secondary solidification and agglomeration of hot steel slag after being poured into the slag pool. It can be directly cooled by water, and the effect of steel slag granulation can be achieved without covering and hot stuffing. The f-MgO and f-CaO in the steel slag are reduced by 50% year-on-year, achieving the process goal of direct resource utilization of steel slag after water quenching. It is a new type of short-process steel slag treatment process.

[0009] The innovative features of the present invention are as follows: 1. Use the heat energy of hot slag as the thermodynamic condition of carbothermal reduction reaction to reduce the iron oxide in the slag, so that more than 50% of the high-valent iron oxide in the slag is reduced to metallic iron and low-valent magnetic iron, which is convenient for the screening and magnetic separation of the slag; 2. Use the heat insulation function of fly ash to control the carbon-oxygen reaction rate after coal slime is added to liquid steel slag, eliminating potential fire safety hazards during the process implementation; 3. After reducing the ferrite in the steel slag, the phenomenon of secondary crystallization and solidification of the steel slag is reduced, and the ability of cooling water to penetrate downward during the water cooling process is improved, making the process of water quenching the steel slag more convenient; 4. Use Al2O3+SiO2 in fly ash to react with f-MgO and f-CaO in steel slag to eliminate the hidden dangers of steel slag resource utilization and replace the process of using high-pressure steam to digest f-MgO and f-CaO in the hot slag process; 5. During the process of CO gas escape generated by carbon-oxygen reaction, penetrating pores are formed in the steel slag, which facilitates the cooling water to penetrate the bottom during the water cooling process and complete the water quenching process of the steel slag; 6. After the ferrite in the steel slag is reduced by carbon thermal reaction, the independent 2CaO·SiO2 mineral phase in the steel slag increases. During the slow cooling process, β-2CaO·SiO2 transforms into γ-2CaO·SiO2, which can cause a 5% volume expansion, which is conducive to the natural fragmentation of the steel slag and the detachment of the steel slag from the surface of the steel block in the steel slag, which is conducive to the recovery of slag steel in the steel slag; 7. The carbon thermal reaction can be used to reduce and remove phosphorus in tricalcium phosphate adhering to the surface of slag steel, which is beneficial to reduce the risk of phosphorus reversion caused by slag steel utilization in steelmaking.

[0010] The beneficial contributions of the present invention are as follows: carbon thermal reaction is used to reduce the temperature of steel slag, which is beneficial to reducing water consumption in the steel slag treatment process; the process can omit the covered and pressed hot stuffing step of hot stuffing slag treatment, which can reduce the steel slag treatment cycle and eliminate potential safety hazards such as explosion during the hot stuffing process of the original steel slag; the cost of steel slag treatment is greatly reduced; the iron-containing materials recovered from the steel slag are increased, which is beneficial to improving the economic benefits of the steel plant; fly ash and coal slime are both wastes of Ruixiang Coking Plant, and after resource utilization, it is beneficial to Yigang to reduce the overall amount of solid waste. DETAILED DESCRIPTION

[0011] The present invention is described by taking the slag treatment production line of Yili Steel as an example: A method for treating Yigang slag in a short process is implemented according to the following steps: 1) Transport the fly ash and coal sludge from Yigang Ruixiang Coking Plant to the dry powder pelletizing production line for standby use; 2) Fly ash and coal slime are mixed evenly in a mass percentage ratio of 30%:70%, and then produced into pellets with a particle size of 10-20 mm by a high-pressure dry powder briquetting machine; the above pellets are transported to a hot slag pool for standby use; wherein the carbon content of the coal slime is 33%-35%; 3) At the beginning of the slag treatment process, a layer of hot steel slag is first poured into the bottom of the hot slag pool, and the above pellets are added to the top of the steel slag. The amount of pellets added is 300-500kg per ton of steel slag; 4) After adding the pellets, continue to pour liquid slag on the top of the pellets. After pouring the liquid slag, there is no need to use an excavator to stir it. Wait for the liquid slag to solidify and continue to add the above pellets to the slag surface. Repeat the above operation until the slag pool is filled with slag. 5) After the slag pool is filled with steel slag, slowly cool it for 4 hours, and then spray water into the slag pool to cool it; 6) The slag pool does not need to be covered or kept hot. It only needs to be cooled to about 100°C by pumping water. Then the slag is dug out by an excavator and directly put into the slag screening and magnetic separation process. The iron-containing materials separated by the magnetic separation are returned to the steel plant for recycling, and the tailings are directly utilized as raw materials for road projects, cement production, and building materials.

Claims

1. A method for treating Yigang steel slag in a short process, characterized in that: Follow these steps to implement: 1) Transport the fly ash and coal sludge from Yigang Ruixiang Coking Plant to the dry powder pelletizing production line for standby use; 2) Fly ash and coal slime are mixed evenly in a mass percentage ratio of 30%:70%, and then produced into pellets with a particle size of 10-20 mm by a high-pressure dry powder briquetting machine; the above pellets are transported to a hot slag pool for standby use; wherein the carbon content of the coal slime is 33%-35%; 3) At the beginning of the slag treatment process, a layer of hot steel slag is first poured into the bottom of the hot slag pool, and the above pellets are added to the top of the steel slag. The amount of pellets added is 300-500kg per ton of steel slag; 4) After adding the pellets, continue to pour liquid slag on the top of the pellets. After pouring the liquid slag, there is no need to use an excavator to stir it. Wait for the liquid slag to solidify and continue to add the above pellets to the slag surface. Repeat the above operation until the slag pool is filled with slag. 5) After the slag pool is filled with steel slag, slowly cool it for 4 hours, and then spray water into the slag pool to cool it; 6) The slag pool does not need to be covered or kept hot. It only needs to be cooled to 100°C by pumping water. Then the slag is dug out by an excavator and directly put into the slag screening and magnetic separation process. The iron-containing materials separated by the magnetic separation are returned to the steel plant for recycling, and the tailings are directly utilized as raw materials for road projects, cement production, and building materials.