A resource recovery process for 300 series stainless steel slag

Abstract

The present application relates to the technical field of recycling and reuse of stainless steel slag, in particular, a resource recovery process applied to 300 series stainless steel slag, comprising the following steps: firstly, the liquid stainless steel slag produced by the AOD furnace is packaged to obtain 300 series oxidized slag and 300 series slag reduced slag, and then the 300 series oxidized slag is subjected to roller crushing, heat exchange with a membrane cooler, crushing and screening, ball milling, and gravity air separation to recover iron concentrate and tailings, and the 300 series slag reduced slag is subjected to roller crushing, heat exchange with a membrane cooler, crushing, ball milling, and gravity air separation to recover iron concentrate and tailings; at the same time, the waste heat of the liquid steel slag is recovered, and the heat of the roller section is used to upgrade the low-quality steam to a higher-quality steam. The present application can recover metals and heat energy from the difficult-to-treat 300 series stainless steel slag, realize green and clean recovery, and solve the technical problem that the 300 series stainless steel slag needs to be treated by wet method.

Description

Technical Field

[0001] The present application relates to the technical field of recycling and reuse of stainless steel slag, and in particular to a resource recovery process applied to 300 series stainless steel slag. Background Art

[0002] The existing domestic stainless steel slag resource recovery process does not distinguish and recycle 300 series stainless steel slag. The technical characteristics of 300 series stainless steel slag treatment are as follows: 1. The calcium oxide content of 300 series stainless steel slag is high, and its volume expands after absorbing water, resulting in pulverization; 2. The 300 series stainless steel slag undergoes a crystal transformation of dicalcium silicate at around 600°C, and its volume expansion causes pulverization, making it difficult to control dust; 3. The powder easily aggregates when it comes into contact with water, affecting the dust removal effect; 4. 300 series steel slag is non-magnetic, and conventional magnetic separation methods cannot select the steel blocks in it in time, resulting in hard steel blocks (alloys) that easily damage the crushing equipment; 5. The heat recovery efficiency is low.

[0003] The current traditional steel slag treatment methods in China mostly use natural air cooling, hot pouring, pool stewing, etc. for primary treatment; the secondary treatment basically uses the process of crushing + wet grinding + gravity shaker sorting. Therefore, the current status of domestic stainless steel slag treatment has the following problems: basically, a large amount of water is required to cool the stainless steel slag, which consumes a lot of water; the tailings from wet grinding have low activity and high treatment costs; the production environment of wet grinding is poor and does not meet the requirements of clean production and ultra-low emissions; the heat energy is not effectively recovered, and the heat energy recovery efficiency is low. To this end, the present application provides a resource recovery process for 300 series stainless steel slag that is efficient, environmentally friendly, and can effectively recover heat energy. Summary of the invention

[0004] In order to solve the above technical problems, the present application provides a resource recovery process applied to 300 series stainless steel slag.

[0005] The present application provides a resource recovery process for 300 series stainless steel slag, which is achieved through the following technical solutions:

[0006] A resource recovery process for 300 series stainless steel slag, comprising the following steps:

[0007] Step 1, the liquid stainless steel slag produced by the AOD furnace is packaged to obtain 300 series oxidized slag and 300 series slag reduced slag;

[0008] Step 2: For the 300 series oxide slag, the temperature is first reduced to 1000-1150°C by roller crushing, and the slag is transformed from liquid to solid. The solid slag is transferred to a membrane cooler for heat exchange. The high-pressure hot water obtained by heat exchange in the membrane cooler is heated by a flash evaporation system to obtain steam A. The steam A has a pressure of 0.4-0.8MPa and a temperature of 150-175°C. The hot air generated during the roller crushing process is introduced into a waste heat boiler to produce steam B. The steam B has a pressure of 1.0-2.0MPa and a temperature of 1 85℃-212.2℃, or the steam A generated by the flash evaporation system is heated through the roller pressing area to heat the steam A into high-quality steam C, the obtained steam C has a pressure of ≥1.6MPa and a temperature of 250-300℃, and the steam A, the steam B, and the steam C can be used for power generation or enter the steam network, or for drying materials; the steel slag obtained by heat exchange in the membrane cooler has been cooled to below 100℃, and is successively crushed and screened, ball milled, screened, and gravity air separation to obtain recovered iron concentrate and oxide slag tailings;

[0009] The 300 series reducing slag is firstly cooled to 1100-1250°C by roller crushing, and the slag is transformed from liquid to solid. The solid slag is transferred to a membrane cooler for heat exchange. The high-pressure hot water obtained by heat exchange in the membrane cooler is heated by a flash evaporation system to obtain steam D. The pressure of the steam D is 0.4-0.8MPa and the temperature is 150-175°C. The hot air generated in the roller crushing process is introduced into a waste heat boiler to produce steam E. The steam E has a pressure of 1.0-2.0MPa and a temperature of 185°C-212.2°C. Alternatively, the steam D generated by the flash evaporation system is heated in a roller pressing area to be heated to steam F. The pressure of the steam F is ≥1.6MPa and the temperature is 250-300°C. The steam D, steam E and steam F can be used for power generation or enter a steam network, or used for drying materials. The slag obtained by cooling and heat exchange in a membrane cooler is cooled to below 100°C, and is successively screened and gravity air separated to obtain recovered iron concentrate and reducing slag tailings.

[0010] This application can be used to recover metal and heat energy from the difficult-to-treat 300 series stainless steel slag, thereby achieving green and clean recycling and solving the technical problem of requiring wet treatment of the 300 series stainless steel slag.

[0011] Preferably, the roller crushing treatment time of the roller crusher in step 2 is 5-10 minutes.

[0012] Preferably, the oxidized steel slag obtained through heat exchange in the membrane cooler in the step 2 is cooled to below 100°C, the steel slag is first crushed, and then sieved with a 100mm sieve to screen out steel slag with a block diameter ≥100mm and steel slag with a block diameter <100mm. For the steel slag with a block diameter ≥100mm, the crushing and screening are repeated in multiple cycles until the steel slag screened out by the 100mm sieve has a block diameter <100mm; the steel slag with a block diameter <100mm is input into a ball mill for ball milling and screening to obtain an oversize material with a particle size ≥3mm and a screened material with a particle size <3mm. The oversize material with a particle size ≥3mm is recycled cold steel particles, and the screened material with a particle size <3mm is subjected to gravity air separation to screen out iron concentrate, and the remainder is the oxidized slag tailings product.

[0013] Preferably, the oxidized steel slag obtained by heat exchange in the membrane cooler in the step 2 is cooled to below 100°C, the steel slag is first crushed, and then screened with a 50mm sieve to screen out steel slag with a block diameter ≥50mm and steel slag with a block diameter <50mm. For the steel slag with a block diameter ≥50mm, the crushing and screening are repeated for multiple cycles until the steel slag block diameter screened out by the 50mm sieve is <50mm; the steel slag with a block diameter <50mm is input into a ball mill for ball milling and screening to obtain an oversize material with a particle size ≥1mm and a screened material with a particle size <1mm. The oversize material with a particle size ≥1mm is recycled cold steel particles, and the screened material with a particle size <1mm is subjected to gravity air separation to screen out iron concentrate, and the remainder is the oxidized slag tailings product.

[0014] Preferably, the reduced steel slag obtained by heat exchange in the membrane cooler in the step 2 is cooled to below 100°C, and is first screened to obtain steel slag material with a particle size of <5mm and steel slag particles with a particle size of >5mm; the steel slag with a particle size of <5mm is subjected to gravity air separation to screen out granular steel, and the remainder is the reduced slag tailings product; the steel slag particles with a particle size of >5mm are input into a ball mill for treating oxidized slag for ball milling and screening, the screened material is steel slag with a particle size ≥3mm for recycled cold steel particles, and the screened material is screened material with a particle size of <3mm, and the gravity air separation is used to screen out iron concentrate, and the remainder is the reduced slag tailings product.

[0015] Preferably, the reduced steel slag obtained by heat exchange in the membrane cooler in the step 2 is cooled to below 100°C, and is first screened to obtain steel slag material with a particle size of <3mm and steel slag particles with a particle size of >3mm; the steel slag with a particle size of <3mm is subjected to gravity air separation to screen out granular steel, and the remainder is the reduced slag tailings product; the steel slag particles with a particle size of >3mm are input into a ball mill for treating oxidized slag for ball milling and screening, the screened material is steel slag with a particle size ≥1mm for recycled cold steel particles, and the screened material is screened material with a particle size of <1mm, and the gravity air separation is used to screen out iron concentrate, and the remainder is the reduced slag tailings product.

[0016] Preferably, the crushing and stirring roller in the roller crusher used in step 2 is evenly distributed with crushing teeth, the crushing teeth are triangular or square columnar in shape, and arranged in a wave shape, and the distribution density of the crushing teeth on the crushing and stirring roller is 0.01-0.3 pieces / 100cm 2 .

[0017] By adopting the above technical solution, the contact between stainless steel slag and air can be reduced, oxidation can be reduced, the temperature of stainless steel slag turning from liquid to solid is about 1000-1200℃, the crushing and stirring time needs to be controlled short, the stainless steel slag can retain more heat, which is convenient for subsequent recovery of more heat, reducing the overall production energy consumption, and improving resource utilization.

[0018] In summary, this application has the following advantages:

[0019] 1. This application can recover metal and heat energy from the difficult-to-treat 300 series stainless steel slag, achieve green and clean recycling, and solve the technical problem that 300 series stainless steel slag needs to be treated by wet method.

[0020] 2. This application completely changes the current situation of wet processing of 300 series stainless steel slag, which has a poor production environment and does not meet the requirements of clean production and ultra-low emissions. It realizes dry processing of 300 series stainless steel slag and can effectively recover the heat energy of the slag to produce higher quality steam for power generation or input into the steam network. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a process flow chart of resource recovery applied to 300 series oxide slag in an embodiment of the present application.

[0022] Figure 2 It is a resource recovery process flow chart applied to 300 series reduction slag in the embodiments of the present application. DETAILED DESCRIPTION

[0023] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples and comparative examples. Example

[0024] A resource recovery process applied to 300 series stainless steel slag includes a process for recovering available metal resources from 300 series reduction slag, a process for recovering available steel resources from 300 series oxidation slag, a process for recovering thermal energy resources from 300 series reduction slag, and a process for recovering thermal energy resources from 300 series oxidation slag.

[0025] A resource recovery process for 300 series stainless steel slag, specifically comprising the following steps:

[0026] Step 1, the stainless steel slag produced by the AOD furnace is packaged to obtain 300 series oxidized slag and 300 series slag reduced slag;

[0027] Step 2, reference Figure 1 The process for recovering the usable metal resources of 300 series oxidized stainless steel slag is as follows: the 300 series oxidized slag outputted from the AOD furnace is connected to a slag basin and transported to a steel slag processing line. The slag basin is clamped by an automatic bag turning machine and poured into a roller crusher for roller crushing for 10 minutes. Crushing teeth are evenly distributed on the crushing and stirring rollers of the roller crusher. The crushing teeth are triangular or square columnar in shape and arranged in a wave shape. In the embodiment, the crushing teeth arranged in a triangular wave shape are specifically used, and the density of the crushing teeth is 0.3 pieces / 100cm 2 By increasing the crushing tooth density on the crushing and stirring roller, the overall roller crushing efficiency is improved, and the roller crushing time is shortened to 10 minutes. After roller crushing, the liquid slag is converted into block solid slag at 1100-1120℃. The obtained block solid slag is transferred to the membrane cooler for heat exchange. After heat exchange in the membrane cooler, the block solid slag with a temperature of <100℃ is obtained. The block solid slag <100℃ is first crushed and then sieved with a 100mm sieve. The sieved block slag with a diameter of ≥100mm The screened steel slag with a block size of <100mm is crushed and screened for block size ≥100mm for multiple cycles until the steel slag block size screened out by the 100mm sieve is <100mm; the screened steel slag with a block size <100mm is input into the ball mill for ball milling and screening to obtain the oversize material with a particle size ≥3mm and the screened material with a particle size <3mm. The oversize material with a particle size ≥3mm is recycled cold steel particles, and the screened material with a particle size <3mm is subjected to gravity air separation to screen out iron concentrate, and the remainder is the oxidation slag tailings product.

[0028] The thermal energy resource recovery process of 300 series oxidized slag is as follows: 300 series oxidized slag is first cooled to 1000-1150℃ by roller crushing, and the slag is transformed from liquid to solid. The solid slag is transferred to a membrane cooler for heat exchange. The high-pressure hot water obtained by heat exchange in the membrane cooler is heated by a flash evaporation system to obtain steam A. The steam A has a pressure of 0.4-0.8MPa and a temperature of 150-175℃. The hot air generated during the roller crushing process is introduced into a waste heat boiler to produce steam B. The pressure of steam B is 1.0-2.0 MPa and a temperature of 185-212.2°C; or the steam A generated by the flash evaporation system is heated through a roller pressing area, and the steam A is further heated to steam C, and the resulting steam C has a pressure ≥1.6MPa and a temperature of 250-300°C. The above steam A, steam B, and steam C can be used for power generation or enter a steam network, or for drying materials; the steel slag obtained by heat exchange in a membrane cooler has been cooled to below 100°C, and is successively crushed and screened, ball milled, screened, and gravity air separation to obtain recovered iron concentrate and oxide slag tailings.

[0029] refer to Figure 2The process for recovering the available steel resources of 300 series reduced stainless steel slag is as follows: the 300 series reduced slag outputted from the AOD furnace is connected to a slag basin and transported to a steel slag processing line. The slag basin is clamped by an automatic bag turning machine and poured into a roller crusher for roller crushing for 5 minutes. Crushing teeth are evenly distributed on the crushing and stirring rollers of the roller crusher. The crushing teeth are triangular or square columnar in shape and arranged in a wave shape. In the embodiment, the crushing teeth arranged in a triangular wave shape are specifically used, and the density of the crushing teeth is 0.3 pieces / 100cm 2 , by increasing the crushing tooth density on the crushing and stirring roller to improve the overall roller crushing efficiency, shorten the roller crushing time to 5min, after roller crushing treatment, the liquid steel slag is converted into block solid steel slag of 1180-1200℃, the block solid steel slag is moved into the membrane cooler for heat exchange, after heat exchange in the membrane cooler, the block solid steel slag with a temperature of <100℃ is obtained, firstly, it is screened with a 5mm sieve to obtain steel slag material with a particle size of <5mm and steel slag particles with a particle size of >5mm; the steel slag with a particle size of <5mm is gravity-selected by air separation to screen out granular steel, and the rest is the reduction slag tailings product; the steel slag particles with a particle size of >5mm are input into the ball mill for treating oxidized slag for ball milling and screening treatment, the sieved material is steel slag with a particle size ≥3mm for recycled cold steel particles, and the sieved material is the sieved material with a particle size of <3mm, the gravity-selected air separation screens out iron concentrate, and the rest is the reduction slag tailings product.

[0030] The thermal energy resource recovery process of 300 series reduction slag is as follows: 300 series reduction slag is first cooled to 1000-1150℃ by roller crushing, and the slag is transformed from liquid to solid. The solid slag is transferred to a membrane cooler for heat exchange. The high-pressure hot water obtained by heat exchange in the membrane cooler is heated by a flash evaporation system to obtain steam D. The pressure of steam D is 0.4-0.8MPa and the temperature is 150-175℃. The hot air generated in the roller crushing process is introduced into the waste heat boiler to produce steam E. The steam pressure of E is 1.0-2.0MPa and the temperature is 185-212.2℃; or the steam D generated by the flash evaporation system is heated through the roller pressing area, and the steam D is further heated to steam F, and the obtained steam F has a pressure of ≥1.6MPa and a temperature of 250-300℃. The above steam D, steam E, and steam F can be used for power generation or enter the steam network, or for drying materials; the steel slag obtained by heat exchange in the membrane cooler has been cooled to below 100℃, and is successively crushed and screened, ball milled, screened, and gravity air separation to obtain recovered iron concentrate and reduced slag tailings.

[0031] Preferably, step 2, refer to Figure 1The process for recovering the usable metal resources of 300 series oxide slag is as follows: the 300 series oxide slag outputted from the AOD furnace is connected to a slag basin and transported to a slag processing line. The slag basin is clamped by an automatic bag turning machine and poured into a roller crusher for roller crushing for 5 minutes. Crushing teeth are evenly distributed on the crushing and stirring rollers of the roller crusher. The crushing teeth are triangular or square columnar in shape and arranged in a wave shape. In the embodiment, triangular wavy crushing teeth are specifically used, and the density of the crushing teeth is 0.3 / 100cm 2 By increasing the crushing tooth density on the crushing and stirring roller, the overall roller crushing efficiency is improved, and the roller crushing time is shortened to 5 minutes. After roller crushing, the liquid slag is converted into block solid slag at 1100-1120℃. The obtained block solid slag is transferred to the membrane cooler for heat exchange. After heat exchange in the membrane cooler, the block solid slag with a temperature of <100℃ is obtained. The block solid slag <100℃ is first crushed and then sieved with a 50mm sieve. The screened block size ≥50mm The slag and the screened steel slag with a block size of <50mm, and the screened steel slag with a block size of ≥50mm are crushed and screened for multiple cycles until the steel slag block size screened out by the 50mm sieve is <50mm; the screened steel slag with a block size of <50mm is input into the ball mill for ball milling and screening to obtain the screened material with a particle size of ≥1mm and the screened material with a particle size of <1mm, the screened material with a particle size of ≥1mm is recycled cold steel particles, and the screened material with a particle size of <1mm is subjected to gravity air separation to screen out iron concentrate, and the remaining material is the oxidation slag tailings product.

[0032] refer to Figure 2 The available technical resource recovery process of 300 series reduction slag is as follows: the 300 series reduction slag output by the AOD furnace is connected to the slag basin and transported to the steel slag processing line. The automatic bag turning machine clamps the slag basin and pours it into the roller crusher for roller crushing for 5 minutes. The crushing and stirring rollers on the roller crusher are evenly distributed with crushing teeth. The geometric shape of the crushing teeth is triangular or square columnar and arranged in a wave shape. The embodiment specifically uses triangular wavy crushing teeth, and the density of the crushing teeth is 0.3 / 100cm 2, by increasing the crushing tooth density on the crushing and stirring roller to improve the overall roller crushing efficiency, shorten the roller crushing time to 5min, after roller crushing treatment, the liquid steel slag is converted into block solid steel slag of 1180-1200℃, the block solid steel slag is moved into the membrane cooler for heat exchange, after heat exchange in the membrane cooler, the block solid steel slag with a temperature of <100℃ is obtained, firstly, it is screened with a 3mm sieve to obtain steel slag material with a particle size of <3mm and steel slag particles with a particle size of >3mm; the steel slag with a particle size of <3mm is gravity-selected by air separation to screen out granular steel, and the rest is the reduction slag tailings product; the steel slag particles with a particle size of >3mm are input into the ball mill for treating oxidized slag for ball milling and screening treatment, the sieved material is steel slag with a particle size ≥1mm for recycled cold steel particles, and the sieved material is the sieved material with a particle size of <1mm, the gravity-selected air separation screens out iron concentrate, and the rest is the reduction slag tailings product.

[0033] In summary, the present application can carry out metal recovery and heat energy recovery for the difficult-to-treat 300 series stainless steel slag, thereby achieving green and clean recovery and solving the technical problem that the 300 series stainless steel slag needs to be treated by wet method.

Claims

1. A resource recovery process for 300 series stainless steel slag, characterized by: The following steps are involved: Step 1: The liquid stainless steel slag produced by the AOD furnace is packaged to obtain 300 series oxidation slag and 300 series reduction slag; Step 2: For the 300 series oxide slag, the temperature is first reduced to 1000-1150°C by roller crushing, and the slag is transformed from liquid to solid. The solid slag is transferred to a membrane cooler for heat exchange. The high-pressure hot water obtained by heat exchange in the membrane cooler is heated by a flash evaporation system to obtain steam A. The steam A has a pressure of 0.4-0.8MPa and a temperature of 150-175°C. The hot air generated during the roller crushing process is introduced into a waste heat boiler to produce steam B. The steam B has a pressure of 1.0-2.0MPa and a temperature of 150-175°C. The temperature is 185℃-212.2℃, or the steam A generated by the flash evaporation system is heated through the roller pressing area to heat the steam A into high-quality steam C. The obtained steam C has a pressure of ≥1.6MPa and a temperature of 250-300℃. The steam A, steam B and steam C can be used for power generation or enter the steam network, or for drying materials. The steel slag obtained by heat exchange in the membrane cooler has been cooled to below 100℃, and is successively crushed and screened, ball milled, screened and gravity air separation to obtain recovered iron concentrate and oxide slag tailings. The 300 series reducing slag is firstly cooled to 1100-1250°C by roller crushing, and the slag is transformed from liquid to solid. The solid slag is transferred to a membrane cooler for heat exchange. The high-pressure hot water obtained by heat exchange in the membrane cooler is heated by a flash evaporation system to obtain steam D. The pressure of steam D is 0.4-0.8MPa and the temperature is 150-175°C. The hot air generated in the roller crushing process is introduced into a waste heat boiler to produce steam E. The pressure of steam E is 1.0-2.0MPa and the temperature is 185°C-212.2°C; or the steam D generated by the flash evaporation system is heated by a roller pressing area to heat steam D to steam F. The pressure of the obtained steam F is ≥1.6MPa and the temperature is 250-300°C. The above steam D, steam E and steam F can be used for power generation or enter the steam network, or used for drying materials; the slag obtained by cooling and heat exchange in the membrane cooler is cooled to below 100°C, and is successively screened and gravity air separated to obtain recovered iron concentrate and reducing slag tailings.

2. The resource recovery process for 300 series stainless steel slag according to claim 1, characterized in that: The oxidized steel slag obtained by heat exchange in the membrane cooler in the step 2 is cooled to below 100° C. The steel slag is first crushed and then screened using a 100 mm sieve to screen out steel slag with a block diameter ≥100 mm and steel slag with a block diameter <100 mm. For the steel slag with a block diameter ≥100 mm, the crushing and screening processes are repeated for multiple cycles until the steel slag block diameter screened out by the 100 mm sieve is <100 mm; the steel slag with a block diameter <100 mm is input into a ball mill for ball milling and screening to obtain an oversize material with a particle size of ≥3 mm and a screened material with a particle size of <3 mm. The oversize material with a particle size of ≥3 mm is recycled cold steel particles, and the screened material with a particle size of <3 mm is subjected to gravity air separation to screen out iron concentrate, and the remaining material is the oxidized slag tailings product.

3. The resource recovery process for 300 series stainless steel slag according to claim 2, characterized in that: The reduced steel slag obtained by heat exchange in the membrane cooler in the step 2 is cooled to below 100° C. The steel slag is first crushed and then screened using a 50 mm sieve to screen out steel slag with a block diameter ≥50 mm and steel slag with a block diameter <50 mm. For the steel slag with a block diameter ≥50 mm, the crushing and screening processes are repeated for multiple cycles until the steel slag block diameter screened out by the 50 mm sieve is <50 mm; the steel slag with a block diameter <50 mm is input into a ball mill for ball milling and screening to obtain screened material with a particle size ≥1 mm and screened material with a particle size <1 mm. The screened material with a particle size ≥1 mm is recycled cold steel grains, and the screened material with a particle size <1 mm is subjected to gravity air separation to screen out iron concentrate, and the remaining material is the reduced slag tailings product.

4. The resource recovery process for 300 series stainless steel slag according to claim 1, characterized in that: The crushing and stirring rollers in the roller crusher used in step 2 are evenly distributed with crushing teeth, the geometric shape of the crushing teeth is triangular or square columnar, and the distribution density of the crushing teeth on the crushing and stirring rollers is 0.01-0.3 / 100cm 2 .

5. The resource recovery process for 300 series stainless steel slag according to claim 1, characterized in that: The roller crushing process time of the roller crusher in the step 2 is 5-10 minutes.

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