Steel slag whole-process dry-method treatment process and steel slag whole-process dry-method treatment system

Abstract

The invention discloses a steel slag whole-process dry treatment process, and belongs to the technical field of steel slag treatment. Comprising the following steps: S1, a rolling procedure: carrying out rolling crushing on liquid steel slag, and in the process, cooling by adopting an air cooling mode to solidify the liquid steel slag; s2, a cooling procedure, wherein the steel slag obtained in the step S1 is cooled to 100 DEG C or below in a non-air-cooling mode; s3, a grinding procedure; s4, a sorting procedure; and S5, a waste heat recovery process, wherein heat released by the steel slag in the rolling process and the cooling process is recycled. The invention further discloses a steel slag whole-process dry processing system. Through reasonable design, gradient cooling is formed in the rolling procedure and the cooling procedure, meanwhile, heat released by steel slag in the two procedures is recycled, and the problem that the steel slag treatment waste heat recovery rate is low is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of steel slag treatment, and in particular to a full-process dry treatment process and system for steel slag. Technical Background

[0002] Steel slag is a waste generated during steel production. In order to reduce environmental pollution in steel plants, it needs to be treated and ensure that the treatment of steel slag meets the principle of "low input, fast output, maximum benefit, and increased steel recovery". Steel slag includes carbon steel slag, stainless steel slag, etc. Compared with the treatment process of carbon steel slag, the treatment process of stainless steel slag has the following characteristics: ① High calcium oxide, volume expansion after absorbing water, resulting in pulverization; crystal transformation of dicalcium silicate occurs at around 600°C, volume expansion leads to pulverization, and dust is difficult to control; ② Powder is easy to stick together when it comes into contact with water, affecting the effect of magnetic separation and dust removal; ③ 300 series 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 crushing equipment.

[0003] The treatment process of stainless steel slag generally adopts wet process, which consumes a lot of water, causes sewage to flow on site, and muddy tailings yard, which seriously does not meet the requirements of clean production. Therefore, wet process will be gradually eliminated, and dry process will become the mainstream process of stainless steel slag treatment.

[0004] Chinese patent CN114939591B discloses a dry separation process for stainless steel slag, which consists of four process sections: stainless steel molten slag casting slag jaw crushing, electric furnace slag ball milling separation, AOD slag dry rapid cooling ball milling separation and AOD slag dry balanced cooling slow cooling pulverization separation. The products of the electric furnace slag ball milling separation are lump steel grain steel, steel fine powder and electric furnace slag fine powder. The products of the AOD slag dry rapid cooling ball milling separation are lump steel, grain steel, steel fine powder and β-C2S phase fine slag powder. The products of the AOD slag dry balanced cooling pulverization separation are lump steel grain steel, steel fine powder and γ-C2S phase fine slag powder. The steel lump steel grains are returned to steelmaking for recycling, the steel fine powder is used as sintering raw material, and the electric furnace slag fine powder, γ-C2S phase fine slag powder and β-C2S phase fine slag powder are used as auxiliary materials for cement production. Although this patent adopts a dry sorting process, it does not recycle the waste heat generated during the processing. On the one hand, it causes a lot of resource waste and does not meet the principle of maximizing benefits. On the other hand, the existence of waste heat increases the load on the processing system and increases the maintenance cost of the equipment.

[0005] Chinese patent CN115522001A discloses a dry treatment method for stainless steel slag, and the specific operation steps of the method are as follows: Step 1: hot crushing, condensing the molten stainless steel slag into a flat plate through a flat plate casting machine, and crushing the stainless steel refined slag into fragments with a single roller crusher; Step 2: adding the fragments in step 1 to a dry cooler, completing phase change in the dry cooler, and generating hot air greater than 300°C for 3000m 3 / ton, the waste heat is used for drying, generating steam or generating electricity; Step three: dry crushing, the steel slag in step two is crushed by a rod mill, and then fed to a roller press by an elevator for extrusion to form a cake, the crushed steel slag is passed through a fan to use gravity to separate the metal that cannot be crushed from the steel slag, so as to realize the recovery of the metal in the stainless steel slag and obtain the first steel slag powder at the same time; Step four: The steel slag ultrafine powder extrusion and grinding system includes a roller press and an ultrafine ball mill, the roller press and the air flow classifier form a closed circuit, and the ball mill is open circuit, the first steel slag powder is fed into a steady flow weighing bin by a elevator through a belt conveyor and an automatic iron remover, the material in the bin is extruded by a roller press to form a cake, which is fed to an air flow classifier by an elevator for sorting, the sorted coarse powder is returned to the roller press for re-extrusion, the sorted fine powder is fed to the ball mill for grinding, and the milled material obtains the second steel slag powder. Although this patent includes waste heat recovery, it only recovers the heat generated by the dry cooler, and does not recover the heat from the hot crushing step, so the waste heat recovery rate is still relatively low. Summary of the invention

[0006] In view of the above problems, the present invention provides a full-process dry treatment process for steel slag. Through reasonable design, the rolling process and the cooling process form a gradient cooling, and the heat released by the steel slag in these two processes is recovered at the same time, solving the problem of low waste heat recovery rate in steel slag treatment.

[0007] To achieve the above object, the present invention adopts the following technical solution:

[0008] A full-process dry treatment process for steel slag, comprising:

[0009] S1. Rolling process, the liquid slag is crushed by rollers, during which the liquid slag is cooled by air cooling to solidify;

[0010] S2. A cooling step, wherein the slag obtained in step S1 is cooled to below 100°C by a non-air cooling method; the non-air cooling method is also a non-wet cooling method;

[0011] S3. Grinding process;

[0012] S4. Sorting process;

[0013] S5. A waste heat recovery process, in which the heat released by the steel slag in the rolling process and the cooling process is recovered and processed to generate steam.

[0014] Compared with the wet treatment process, in which slag pulverization leads to difficulty in heat recovery, thus causing a large amount of waste heat resources to be wasted, the full-process dry process of the present invention adopts gradient cooling, wherein the temperature of the rolling process is high, and air cooling is adopted for cooling, and the heat exchange efficiency is high; the cooling process adopts a non-air cooling method to cool, thereby avoiding the influence of slag pulverization on the air cooling method and the risk of metal oxidation. Therefore, in the entire heat recovery process, slag pulverization has little effect, thereby realizing the recovery of slag treatment heat and reducing resource waste; on the other hand, timely discharging heat from the equipment in the rolling process and the cooling process can greatly reduce the load of the equipment and ensure that the cooling can be carried out smoothly.

[0015] Preferably, in step S1, the cooling medium of the air cooling method is the tail wind discharged from the waste heat recovery process. By blowing the tail wind discharged after waste heat recovery back into the roller pressing process for recycling, on the one hand, the tail wind discharged after waste heat recovery is recycled, which improves the resource recycling rate and reduces the load of the waste heat recovery system; on the other hand, the cooling medium has the characteristic of reduced oxygen content due to the reaction with steel slag. Using it as a cooling medium reduces the possibility of steel slag being oxidized, thereby improving the recovery rate of metallic iron.

[0016] Preferably, the temperature of the tail wind is 130-180°C.

[0017] Preferably, the cooling medium controls the wind speed to be 5-30 m / s.

[0018] Preferably, the cooling medium controls the wind speed to be 10-20 m / s.

[0019] Preferably, in step S1, the temperature of the steel slag after rolling is 800-1000°C.

[0020] Preferably, in step S1, the rolling time is 5 to 30 minutes.

[0021] The speed of wind and the temperature of steel slag after rolling have certain influence on the rolling time, the particle size of steel slag after rolling crushing, the final metal recovery rate and waste heat recovery rate, and even the output of the entire steel slag treatment. The present invention selects a suitable wind speed and controls the temperature of steel slag after rolling within a reasonable range, so as to obtain a higher metal recovery rate and waste heat recovery rate, and keep the steel slag treatment output at a higher level.

[0022] Preferably, in step S1, the temperature of the liquid slag before roller crushing is 1300-1600°C.

[0023] Preferably, in step S1, the particle size of the steel slag after rolling is less than 50 mm. Since the film cooler has a higher efficiency in recovering waste heat, moving the steel slag with a sufficiently high temperature into the film cooler as soon as possible can obtain a higher waste heat recovery rate; and controlling the particle size of the steel slag after rolling to be less than 50 mm is conducive to the smooth progress of subsequent processes.

[0024] Preferably, in step S2, the non-air cooling cooling device is a film cooler. When the processing volume of steel slag is relatively large, a two-stage film cooler can be used for cooling, thereby improving the cooling efficiency. The film cooler has a cooling water pipe inside, which can quickly cool the steel slag. At the same time, the cooling water in the cooling water pipe is heated to directly produce high-temperature and high-pressure water.

[0025] Preferably, in step S2, the cooling rate is 10-25°C / min.

[0026] Preferably, in step S5, the waste heat recovery process uses a waste heat boiler to recover heat, and the heat recovered by the waste heat boiler is used to generate steam.

[0027] Preferably, a flash evaporation process is further included to flash the high-temperature and high-pressure water generated by the membrane cooler to obtain saturated steam, and the saturated steam is fed into the waste heat boiler. Feeding the saturated steam into the waste heat boiler can increase the temperature and pressure of the steam generated by the waste heat boiler, and further improve the waste heat recovery rate.

[0028] Preferably, the grinding process includes rod milling and ball milling. The purpose of rod milling is coarse grinding and fine crushing. Since ball milling consumes a lot of energy, more crushing and less grinding is more energy-saving. Therefore, the combination of rod milling and ball milling can improve grinding efficiency and reduce energy consumption.

[0029] Preferably, the separation process includes magnetic separation and air separation. According to the chemical composition and physical properties of steel slag, in steel slag, 300 series generally does not show magnetism, while 200 series and 400 series show magnetism. Therefore, the steel separation adopts a combination of magnetic separation and air separation as needed. Through such a treatment method, the useful components in the steel slag can be recovered more effectively, and it also helps to reduce environmental pollution.

[0030] The present invention also provides a full-process dry treatment system for steel slag, including a roller pressing equipment, a cooling equipment, a waste heat recovery system, a grinding system, and a sorting system; the roller pressing equipment is connected to the cooling equipment through a conveying device; the flue gas inlet of the waste heat recovery system is connected to the roller pressing equipment and the cooling equipment, and is used to recover the heat released by the steel slag in the roller pressing process and the cooling equipment; the tail air outlet of the waste heat recovery system is connected to the roller pressing equipment, and the exhausted tail air is blown back into the roller pressing equipment.

[0031] Preferably, the cooling device is a film cooler.

[0032] Preferably, a flash evaporation device is also included, which is connected to the water outlet of the cooling device and flashes the high-temperature and high-pressure water of the cooling device to obtain saturated steam.

[0033] Preferably, the waste heat recovery system comprises a waste heat boiler, a superheater is provided in the waste heat boiler, and the steam outlet of the flash evaporation equipment is connected to the superheater of the waste heat boiler to deliver saturated steam to the waste heat boiler.

[0034] Preferably, the waste heat recovery system also includes dust removal equipment and a circulating fan. The waste heat boiler is connected to the roller pressing equipment and the cooling equipment through a pipeline to collect the heat generated by the roller pressing equipment and the cooling equipment for generating steam; the dust removal equipment is connected to the waste heat boiler through a pipeline to remove dust from the tail wind discharged after the waste heat boiler is utilized; the circulating fan is respectively connected to the dust removal equipment and the roller pressing equipment through pipelines to blow the tail wind after dust removal back to the roller pressing equipment for cooling the gear roller and slag.

[0035] Preferably, the rolling equipment is arranged in a closed space, and the slag pot is tilted in the closed space to prevent fresh air from entering. After the slag is dumped, the slag pot is withdrawn, the door of the closed space is closed, and then the cooling medium wind is introduced to avoid drawing in fresh air. On the one hand, the wind speed and temperature in the closed space can be kept stable, thereby ensuring the stability of the steam in the waste heat boiler; on the other hand, the influence of high oxygen content in the environment on metal oxidation can be further avoided.

[0036] Preferably, the grinding system comprises a rod mill and a ball mill.

[0037] Preferably, the sorting system includes magnetic separation equipment and wind separation equipment.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] (1) The present invention is applicable to the treatment of stainless steel slag, but is not limited to stainless steel slag, and is also applicable to the treatment of other types of slag, such as ordinary carbon steel slag, stainless steel slag, high-temperature smelting gold slag, etc. First, the full-process dry process of the present invention is the first to extract heat from the rolling process, combined with the heat extraction from the cooling process, which greatly improves the waste heat recovery rate. Secondly, the present invention adopts gradient cooling, wherein the rolling process adopts air cooling to cool down, and recovers heat at the same time, thereby improving the heat recovery efficiency of the overall process; the cooling process adopts non-air cooling to cool down, thereby avoiding the impact of slag pulverization on the air cooling method, and avoiding the risk of metal oxidation. During the entire heat recovery process, the slag pulverization has little effect, thereby achieving efficient recovery of slag treatment heat and metal, and reducing resource waste; on the other hand, timely discharge of heat from the equipment of the rolling process and the cooling process can greatly reduce the load of the equipment and ensure that the cooling can be carried out smoothly.

[0040] (2) The present invention recycles the tail wind discharged from the waste heat recovery process by blowing it back into the rolling process. On the one hand, the tail wind discharged after the waste heat recovery process is recycled, thereby improving the resource recovery rate; on the other hand, the cooling medium has the characteristic of lower oxygen content than fresh air. Using it as a cooling medium reduces the possibility of metal oxidation in the steel slag, thereby improving the recovery rate of metallic iron.

[0041] (3) The present invention adopts a membrane cooler as a non-air-cooled cooling device, and a cooling water pipe is arranged inside the membrane cooler to cool the steel slag. The membrane cooler has a higher thermal efficiency than the waste heat boiler. The cooling water in the cooling water pipe of the cooler is heated to directly produce high-temperature and high-pressure water, and then saturated steam is obtained through flash evaporation. The saturated steam is sent to the superheater of the waste heat boiler, which can increase the steam temperature and pressure generated by the waste heat boiler, and further improve the waste heat recovery rate.

[0042] (4) The present invention selects a suitable wind speed and controls the temperature of the steel slag after roller pressing within a reasonable range, so as to obtain an ideal steel slag particle size, thereby obtaining a higher metal recovery rate and waste heat recovery rate, and maintaining the steel slag processing output at a higher level.

[0043] (5) The present invention combines rod milling and ball milling to improve grinding efficiency and reduce energy consumption.

[0044] (6) The present invention combines magnetic separation with air separation, which can more effectively recover the useful components in the steel slag and also helps to reduce environmental pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 The figure is a schematic diagram of the process of treating steel slag using the full-process dry treatment process of the present invention. DETAILED DESCRIPTION

[0046] In order to better present the present invention, it is illustrated by specific implementation cases, which belong to the protection scope of the present invention but do not limit the protection scope of the present invention.

[0047] Example 1

[0048] A full-process dry treatment system for steel slag, including roller pressing equipment, film cooler, flash evaporation equipment, waste heat boiler, dust removal equipment, circulating fan, rod mill, ball mill, magnetic separation equipment and air separation equipment; the roller pressing equipment is connected to the film cooler through a conveying device; the flue gas inlet of the waste heat boiler is connected to the roller pressing equipment and the cooling equipment through a pipeline to collect the heat released by the steel slag in the roller pressing equipment and the cooling equipment; the waste heat boiler has a superheater for generating steam; the inlet of the dust removal equipment is connected to the flue gas outlet of the waste heat boiler through a pipeline to remove dust from the flue gas discharged after the waste heat boiler is used; the circulating fan is connected to the dust removal equipment through pipelines respectively. The outlet of the dust equipment is connected to the roller pressing equipment, and the tail wind after dust removal is blown back to the roller pressing equipment for cooling the gear roller and steel slag; the membrane cooler is provided with a cooling water pipe, and the outlet of the cooling water pipe is connected to the inlet of the flash evaporation equipment. The flash evaporation equipment flashes the high-temperature and high-pressure water in the cooling water pipe to obtain saturated steam. The steam outlet of the flash evaporation equipment is connected to the superheater of the waste heat boiler to transport saturated steam to the superheater of the waste heat boiler; the roller pressing equipment is arranged in a closed space, and the slag pot is tilted in the closed space to prevent fresh air from entering. After the steel slag is dumped, the slag pot is withdrawn, the door of the closed space is closed, and then the cooling medium wind is introduced to avoid the intake of fresh air.

[0049] A full-process dry treatment process for steel slag, using the above-mentioned treatment system, comprises:

[0050] S1. Rolling process, using roller pressing equipment to roll and crush the liquid steel slag at 1300-1600°C, the rolling time is 5-30min, during which the liquid steel slag is cooled by air cooling to solidify; the cooling medium of the air cooling method comes from the tail wind discharged from the waste heat recovery process in step S5, and the wind speed is controlled to be 5-30m / s;

[0051] S2. A cooling step in which the slag obtained in step S1 is cooled to below 100°C by a film cooler at a cooling rate of 10 to 25°C / min; the cooling water in the cooling water pipe of the film cooler is heated to obtain high-temperature and high-pressure water;

[0052] S3 grinding process, the film cooler after cooling the slag particle size control, and then sequentially into the rod mill and ball mill equipment for rod milling and ball milling;

[0053] S4. In the sorting process, the ground slag enters the magnetic separation equipment and the air separation equipment for magnetic separation and air separation;

[0054] S5. Waste heat recovery process, the waste heat boiler recovers the heat released by the steel slag in the roller press and the membrane cooler to generate steam. The flue gas temperature after the waste heat boiler is used is 130-180°C. The dust removal equipment removes dust from the flue gas, and the circulating fan introduces the tail wind after dust removal into the roller press as a cooling medium for cooling the steel slag in the roller press;

[0055] S6. Flash evaporation process: the flash evaporation equipment flashes the high-temperature and high-pressure water generated by the membrane cooler to obtain saturated steam, and sends the saturated steam to the superheater of the waste heat boiler to increase the temperature and pressure of the steam generated by the waste heat boiler.

[0056] In this embodiment, referring to the full-process dry treatment process of steel slag provided above, the wind speed of the cooling medium in the rolling equipment and the temperature of the steel slag after rolling are used as variables, and different treatment groups (as shown in Table 1) are set to examine the influence of these variables on the steel slag treatment effect.

[0057] Table 1 The settings of each treatment group in Example 1

[0058] Group Wind speed of cooling medium / m / s Temperature of slag after rolling / ℃ Process 1 20 900 Process 2 30 800 Process 3 5 1000 Process 4 10 950 Process 5 3 1000 Process 6 35 800 Process 7 5 1100 Process 8 30 700

[0059] Example 2

[0060] The full-process dry treatment process of steel slag provided in Example 1 is basically the same, and is treated with reference to the settings of Treatment 1, with the only difference being that the high-temperature and high-pressure water in the membrane cooler is not flashed to obtain saturated steam and is not sent to the superheater of the waste heat boiler.

[0061] Example 3

[0062] The full-process dry treatment process of steel slag is basically the same as that provided in Example 1, and is treated with reference to the settings of Treatment 1. The only difference is that the tail air discharged from the waste heat recovery treatment is not introduced into the roller pressing equipment for recycling, but fresh air is used as the cooling medium, and the wind speed remains unchanged.

[0063] Comparative Example 1

[0064] The processing method of patent CN115522001A.

[0065] Effect comparison experiment

[0066] 1. Install a flow meter and a pressure gauge on the steam pipeline, read the flow and pressure values ​​of the steam, and obtain the amount and pressure of the steam generated by each treatment group of Example 1, Example 2, and Example 3, respectively, and compare them with Comparative Example 1. The results are shown in Table 2.

[0067] Table 2 Steam production and pressure of each treatment group in Example 1 and Example 2, Example 3, and Comparative Example 1

[0068] Group Steam output / kg / ton Steam pressure / MPa Process 1 300 1.8 Process 2 280 1.5 Process 3 290 1.6 Process 4 295 1.6 Process 5 275 1.4 Process 6 265 1.3 Process 7 270 1.4 Process 8 260 1.3 Example 2 250 1.2 Example 3 270 1.3 Comparative Example 1 200～240 0.8～1

[0069] From Table 2, we can see that:

[0070] (1) In Example 1 of the present invention, the roller pressing equipment and the film cooler in Processing 1 to 4 form a gradient cooling, and the heat generated by the roller pressing equipment and the film cooler is recovered. The amount of steam generated per ton of steel slag is more than 280 kg, and the maximum is 300 kg. The steam pressure is as high as 1.5 to 1.8 MPa, and a higher waste heat recovery rate is achieved. In Example 2, the outlet water of the membrane cooler was not flashed to produce saturated steam, nor was it sent to the superheater of the waste heat boiler, so the steam pressure was also reduced; in Example 3, the wind speed and the temperature of the steel slag after rolling were the same as those in Treatment 1, and fresh air was used as the cooling medium. The temperature difference between the fresh air and the steel slag was large. Although it helped to quickly cool the steel slag, it also led to a large loss of heat during the heat exchange between the steel slag and the cooling medium, thereby reducing the efficiency of the waste heat boiler and affecting the overall waste heat recovery rate; while in Comparative Example 1, only the heat generated by the dry cooler when treating the steel slag was recovered. The amount of steam generated per ton of steel slag was only 200-240 kg, and the pressure was only 0.8-1 MPa, which was lower than that in Example 2 and significantly lower than that in Treatments 1-4.

[0071] (2) Compared with treatment 3, the wind speed in treatment 5 is too slow, which means that it takes a longer time to roll the slag to cool down to 1000°C, affecting the processing capacity and output of the rolling equipment; while the rolling time is too long, the total air volume is relatively large, and the overall wind temperature is reduced, which affects the normal operation of the waste heat boiler and the overall waste heat recovery rate.

[0072] (3) Compared with treatment 2, the wind speed in treatment 6 is too fast, which means that 800°C can be reached in a shorter rolling time. However, the shorter rolling time makes it impossible to obtain the ideal slag particle size. After the slag with too large a particle size enters the cooling process, the heat dissipates slowly and cannot be removed quickly and effectively, thereby reducing the waste heat recovery rate.

[0073] (4) Compared with treatment 3, at the same wind speed, the temperature of the slag after rolling in treatment 7 is relatively high, and the rolling is also completed in a relatively short time. There is a situation where the ideal slag particle size cannot be obtained, resulting in a decrease in the waste heat recovery rate; on the other hand, the slag is not completely solidified due to the high temperature, and will re-stick into large pieces, affecting the normal operation of the membrane cooler, thereby affecting the waste heat recovery rate; moreover, excessively high temperature will also damage the membrane cooler, reduce the service life of the membrane cooler, and easily cause safety accidents.

[0074] (5) Compared with treatment 2, at the same wind speed, the temperature of the slag after rolling in treatment 8 is relatively low, which means that the rolling time is longer and more heat is transferred to the cooling medium of the rolling equipment. The temperature of the slag entering the membrane cooler is relatively low, which greatly reduces the waste heat recovery rate of the membrane cooler. However, in fact, the heat recovery efficiency of the membrane cooler is higher than the recovery efficiency of the waste heat boiler. Therefore, the temperature of the slag after rolling crushing is too low, which does not meet the goal of the present invention to move the slag with a sufficiently high temperature into the membrane cooler as soon as possible for efficient heat extraction.

[0075] 2. Referring to the method for determining the metallic iron content in "GBT 38812.2-2020 Determination of the metallic iron content of direct reduced iron - ferric chloride decomposition potassium dichromate titration method", the metallic iron content of each treatment group in Example 1 and the steel slag in Example 3 before and after treatment was determined, and the metallic iron residual rate was calculated, wherein the average metallic iron content of the liquid steel slag to be treated was 8%, and the metallic iron residual rate (%) = metallic iron content of tailings / metallic iron content of liquid steel slag * 100%, and the results are shown in Table 3.

[0076] Table 3: The content of metallic iron in the tailings and the residual rate of metallic iron in each treatment group of Example 1 and Example 3

[0077]

[0078]

[0079] From Table 3, we can see that:

[0080] (1) Under the treatment process of the present invention, the metallic iron content of the tailings 1 to 4 treated in Example 1 was all below 0.1%, and the metal residual rate was relatively low, indicating that the treatment process of the present invention achieved a high metal recovery rate level.

[0081] (2) Example 3 uses fresh air instead of the tail air discharged from the waste heat recovery process as the cooling medium to cool the steel slag in the roller press. The metal recovery rate is greatly affected because the oxygen content of the fresh air is higher than that of the tail air discharged from the waste heat recovery process. Under high temperature conditions, it is easy to undergo oxidation reaction with the metal in the steel slag, resulting in a decrease in the metal recovery rate.

[0082] (3) In treatments 5 and 8, the wind speed of the cooling medium was too low or the temperature of the slag after rolling was too low, which meant that the rolling time was too long, increasing the possibility of metal oxidation at high temperatures, thereby reducing the metal recovery rate to a certain extent, and also reducing the processing capacity and output of the rolling crushing process. In treatment 6, the wind speed of the cooling medium was too fast. Since the temperature in the rolling equipment was very high, a large amount of tail wind blowing the slag at high temperature would also accelerate the oxidation of metallic iron in the slag, thereby affecting the metal recovery rate. In treatment 7, the slag ended the rolling at a relatively high temperature, indicating that the rolling time was relatively short. Even at an appropriate wind speed, it would be impossible to obtain the ideal slag particle size, and the slag might not even be completely solidified. The cooling effect of the subsequent membrane cooler was greatly affected, and the grinding and sorting effects would also be affected, thereby indirectly affecting the metal recovery rate.

[0083] In summary, the reason why the present invention adopts a two-stage heat extraction method of a rolling process and a cooling process is that the effects are: 1. By reasonably controlling the wind speed and rolling time of the rolling process, the contact time between wind and slag is reduced, metal oxidation is avoided, and the metal recovery rate is improved; 2. By reasonably controlling the wind speed and rolling time of the rolling process, the slag is solidified, and the slag with a sufficiently high temperature is moved into the membrane cooler as soon as possible, because the membrane cooler has a higher efficiency in recovering waste heat, thereby improving the overall waste heat recovery rate; 3. The rolling process uses the dust-removed and purified tail wind to blow back and cool the slag, making full use of the heat of the tail wind, further improving the waste heat recovery rate, and the entire process is more environmentally friendly.

[0084] The above contents are further detailed descriptions of the present invention in combination with specific / preferred implementations, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, they can also make several substitutions or modifications to these described embodiments without departing from the concept of the present invention, and these substitutions or modifications should be regarded as belonging to the protection scope of the present invention.

Claims

1. A full-process dry treatment process for steel slag, characterized in that: include: S1. Rolling process, the liquid slag is crushed by rollers, during which the liquid slag is cooled by air cooling to solidify; S2. A cooling step, wherein the slag obtained in step S1 is cooled to below 100°C by a non-air cooling method; S3. Grinding process; S4. Sorting process; S5. A waste heat recovery process, which recovers and utilizes the heat released by the steel slag in the rolling process and the cooling process.

2. The full-process dry treatment process of steel slag according to claim 1 is characterized in that: In step S1, the cooling medium of the air cooling method is the tail air discharged from the waste heat recovery process.

3. The full-process dry treatment process of steel slag according to claim 2 is characterized in that: The wind speed of the cooling medium is 5 to 30 m / s.

4. The full-process dry treatment process for steel slag according to claim 1 is characterized in that: In step S1, the temperature of the steel slag after roller crushing is 800-1000°C.

5. The full-process dry treatment process for steel slag according to any one of claims 1 to 4, characterized in that: In step S2, the cooling device used in the non-air cooling method is a film cooler.

6. The full-process dry treatment process for steel slag according to claim 5 is characterized in that: In step S5, the waste heat recovery process uses a waste heat boiler to recover heat.

7. The full-process dry treatment process for steel slag according to claim 6, characterized in that: The method also includes a flash evaporation process, in which high-temperature and high-pressure water generated by the membrane cooler is flashed to obtain saturated steam, and the saturated steam is sent to the waste heat boiler.

8. A full-process dry treatment system for steel slag, characterized by: It includes a rolling device, a cooling device, a waste heat recovery system, a grinding system, and a sorting system; the rolling device is connected to the cooling device; the flue gas inlet of the waste heat recovery system is connected to the rolling device and the cooling device, and is used to recover the heat released by the steel slag in the rolling process and the cooling device; the tail air outlet of the waste heat recovery system is connected to the rolling device, and the discharged tail air is blown back into the rolling device.

9. The full-process dry treatment system for steel slag according to claim 8, characterized in that: The cooling device is a film cooler; it also includes a flash evaporation device, which is connected to the water outlet of the cooling device and flashes the high-temperature and high-pressure water of the cooling device to obtain saturated steam.

10. The full-process dry treatment system for steel slag according to claim 9, characterized in that: The waste heat recovery system includes a waste heat boiler, a superheater is arranged in the waste heat boiler, and the steam outlet of the flash evaporation equipment is connected to the superheater of the waste heat boiler to deliver saturated steam to the waste heat boiler.

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