Steel slag hot disintegration treatment method

Abstract

Belonging to the technical field of metallurgical solid waste treatment, the invention provides a steel slag hot disintegration treatment method, which comprises: a pretreatment step of cooling and crushing molten steel slag to obtain solid steel slag; a deslagging step of feeding the solid steel slag into a hot disintegration pool; a hot disintegration step of performing hot disintegration treatment on the solid steel slag in the hot disintegration pool; cooling and deslagging: feeding the steel slag finished product obtained after hot disintegration into a finished product bin; and a post-treatment step of performing magnetic separation treatment on the steel slag finished product. In the hot disintegration step, the total water supply amount in the hot disintegration treatment period is 1-1.2 m < 3 > / t according to the water-slag ratio. The method has the advantages of short treatment period, high efficiency, small water consumption, pulverization rate of not less than 90%, uniform pulverization granularity, remarkable energy-saving and consumption-reducing effects, high waste heat and water resource recycling rate and remarkable production cost, and can be directly used without being crushed subsequently.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgical solid waste treatment, and in particular to a steel slag hot stuffing treatment method. Background Art

[0002] The steel industry is a basic industry of the national economy. The development of the steel industry has continuously increased steel production. As a by-product of steelmaking, steel slag accounts for 8-15% of crude steel production. Therefore, the output of steel slag is also increasing. Actively developing and applying process technologies to improve the utilization rate and added value of steel slag is an important measure for steel enterprises to achieve sustainable development. The mineral composition of steel slag is mainly tricalcium silicate, followed by dicalcium silicate, RO phase (solid solution formed by oxides of magnesium, iron and manganese, namely FeO, MgO and MnO), dicalcium ferrite and free calcium oxide (f-CaO). Among them, f-CaO and f-MgO will hydrate to form Ca(OH)2 and Mg(OH)2 when they meet water in the natural environment, which will cause the volume expansion of building materials, mortar and other products produced using steel slag, thereby reducing their service life and limiting the resource recycling of steel slag. Therefore, steel slag that has not been stabilized has the problem of poor stability and cannot be used as a large number of resources.

[0003] At present, the stabilization treatment process of steel slag has formed a diversified situation worldwide, mainly covering a variety of technologies such as hot stuffing method, hot pouring method, disk pouring method, water quenching method, drum method, wind quenching method, granulation wheel method, etc. Among them, the hot stuffing method occupies an important position in the field of steel slag treatment with its unique advantages. The hot stuffing method uses the sensible heat of high-temperature molten steel slag, the temperature stress generated after it meets water, and the hydrolysis of free calcium oxide to cause the steel slag to break. The content of free calcium oxide (f-CaO) and free magnesium oxide (f-MgO) in the steel slag treated by the hot stuffing method is significantly reduced, thereby ensuring the stability of product performance. This process can not only pulverize the steel slag, but also improve the activity of the steel slag, which is conducive to subsequent resource utilization. The hot stuffing method not only significantly reduces environmental pollution, but also has the advantages of simple process flow, stable equipment operation, low maintenance cost, and high safety factor. In addition, the slag stuffing method also has a wide range of applicability, and both liquid and solid steel slag can be properly treated. However, the traditional hot stuffing treatment method has problems such as long treatment cycle, low cooling efficiency, large water consumption, uneven pulverization particle size, and large amount of subsequent crushing and processing. Therefore, how to improve and optimize the hot stuffing treatment method of steel slag, improve the efficiency and quality of hot stuffing, reduce the cost of hot stuffing, and thus achieve high efficiency of hot stuffing and energy saving and consumption reduction is an urgent problem to be solved by technicians in this field. Summary of the invention

[0004] The invention provides a steel slag hot stuffing treatment method with high efficiency, good quality, energy saving and consumption reduction, and reduced cost, which is used to solve the problems of long treatment cycle, low cooling efficiency, large water consumption, uneven pulverization particle size, and large subsequent crushing processing volume in the existing hot stuffing treatment method.

[0005] To achieve the above-mentioned purpose, the present invention provides a method for hot stuffing treatment of steel slag, comprising: a pretreatment step of cooling and crushing molten steel slag to obtain solid steel slag; a slag discharge step of sending the solid steel slag into a hot stuffing pool; a hot stuffing step of hot stuffing the solid steel slag in the hot stuffing pool; a cooling and slag discharge step of sending the finished steel slag obtained after the hot stuffing into a finished product bin; and a post-treatment step of magnetic separation treatment of the finished steel slag.

[0006] The method of the invention has simple flow, is easy to operate, is environmentally friendly, economical and efficient, has a large slag processing capacity, has high cooling efficiency, and can digest 70-97% of f-CaO and f-MgO in the slag. The digestion effect and pulverization effect are stable, the pulverization rate is not less than 90%, the water consumption is small, the steam is recycled and utilized on a large scale, the energy consumption and environmental pollutant emission levels are low, the energy-saving and consumption-reducing effects are remarkable, the comprehensive power consumption per ton of slag is only 1kW·h / t, and the f-CaO content in the finished slag does not exceed 3%, the water swelling rate is not more than 2%, the volume stability is good, the particle size after pulverization is uniform and less than 40mm, the slag can be directly used in the production of building materials and the like, and has wide applicability. The utilization rate of the finished slag can reach 100%.

[0007] Preferably, in the pretreatment step, the particle size of the solid steel slag obtained is ≤500mm and the temperature is ≤500°C. Using steel slag with a temperature of ≤500°C for hot stuffing can cool down faster, avoid the high steam pressure generated by the higher temperature steel slag and inhibit the hydration reaction, and increase the reaction rate and degree of free calcium oxide and free magnesium oxide with water and steam, so that the self-decomposition and pulverization of the steel slag becomes faster and more thorough, so as to eliminate the unstable factors of the steel slag, completely eliminate the volume expansion of the finished steel slag, and improve its stability and volume stability. The cooling of the molten steel slag during transportation can be carried out by natural cooling, water mist cooling, air cooling and other cooling methods commonly used in the field, without special limitation here, and it is sufficient to ensure that the temperature of the steel slag during the crushing process is ≤500°C.

[0008] Preferably, in the hot stuffing step, the total water supply during the hot stuffing treatment, calculated as a water-slag ratio, is 1-1.2 m 3 More preferably, the total water supply during the hot stuffing treatment, calculated as water-slag ratio, is 1m 3 / t. The total water supply during the hot stuffing period can not only ensure that the moisture content of the finished slag affects the subsequent equipment within the allowable range, but also ensure that the pulverization rate of the slag is maintained at a high level, so that the two are balanced and it is also beneficial to reduce water consumption. During the hot stuffing period, there is no special limit on the specific water supply flow, but it must be precisely interlocked and controlled by the central control system and the steam pressure in the hot stuffing pool. The process is simple and highly automated.

[0009] Preferably, the pressure in the hot stuffy pool is normal pressure. The pressure of the hot stuffy pool is maintained at a relatively low normal pressure state, which can maximize the recovery and reuse of the produced high-temperature steam, improve the thermal energy utilization rate, and at the same time, the low pressure also keeps the reaction rate of f-CaO and f-MgO at a relatively high state, avoiding excessive pressure due to the presence of steam and thus inhibiting the hydration reaction, making the self-decomposition and pulverization of the steel slag faster and more thorough, and improving the pulverization rate and digestion degree.

[0010] Preferably, the specific operation of the pretreatment step is as follows: pour the molten steel slag into a slag tank car, send it to a slag treatment workshop, and crush the solid steel slag formed by cooling until the particle size is reduced to less than 500 mm, and send it to the slag turning vehicle. The temperature of the molten steel slag drops during transportation, which easily forms solid steel slag. Crushing the steel slag with a larger size can ensure that the steel slag has better water permeability and promotes the free calcium oxide contained therein to be hydrated and digested more completely during the hot stuffy treatment.

[0011] Preferably, the particle size of the solid steel slag after crushing is ≤300 mm. After crushing, the particle size of the solid steel slag becomes smaller, the surface area is expanded, and the contact area with water is also larger, which significantly increases the cooling speed, and can also react and digest faster and more completely, so that the pulverization rate is improved.

[0012] Preferably, the specific operation of the slag dumping step is as follows: use a slag turning crane to dump the crushed solid steel slag into the hot stuffy pool. When the loading amount of solid steel slag reaches the preset rated capacity, cover the stuffy pool cover and lock the device, and fill it with water to seal it. The present application adopts a hot stuffy pool with a large slag loading capacity as the main equipment. It has a low construction cost, a simple structure, is easy to build, and is simple to maintain. It has the advantages of not requiring major changes to existing process equipment. Filling the hot stuffy pool with water to seal it effectively can avoid unnecessary losses caused by steam leakage.

[0013] Preferably, the loading amount of solid steel slag is controlled within a range not exceeding 500 mm above the lower edge of the steam pipe of the hot stuffy pool.

[0014] Preferably, the specific operation of the hot stuffing step is as follows: water is sprayed onto the solid steel slag through the internal nozzle of the hot stuffing pool cover, and the hot stuffing treatment begins after the water contacts the solid steel slag. During the hot stuffing period, the nozzle continuously supplies water, and the steam recovery system is started synchronously to recover the generated steam.

[0015] Through water spray cooling, not only can the steel slag be cooled and solidified quickly, but also the thermal stress generated by rapid cooling can cause the steel slag to crack and break. At the same time, a large amount of water and saturated steam can penetrate into the steel slag to react with f-CaO and f-MgO for hydration, and it can also ensure that water and saturated steam react with f-CaO and f-MgO in the steel slag to be converted into calcium hydroxide and magnesium hydroxide, thereby reducing the content of f-CaO and f-MgO in the steel slag and improving the elimination rate of f-CaO and f-MgO. The expansion force generated during the reaction process can also cause the steel slag to crack and pulverize, increasing the degree of pulverization of the steel slag and improving the stability of the finished steel slag. The digestion reaction process of f-CaO and f-MgO is as follows:

[0016] f-CaO+H2O→Ca(OH)2,

[0017] f-MgO+H2O→Mg(OH)2.

[0018] Preferably, during the heat-stuffing period, the water supply pressure of the nozzle is maintained at 0.3-0.4 MPa, and the pressure in the heat-stuffing pool is interlocked to be normal pressure.

[0019] Preferably, the heat-stifling treatment time is 4-6 hours. More preferably, the heat-stifling treatment time is 4 hours.

[0020] Preferably, the steam recovery system is connected to the heating system, the high-temperature steam system, or the steam condensation recovery treatment system, and the condensed water generated by the steam condensation recovery treatment system is reused in the water supply system for heat treatment. The steam recovery system can timely recover the high-temperature steam in the heat treatment pool to solve the problem of steam diffusion and ensure the constant pressure in the heat treatment pool. In the heating season, the recovered high-temperature steam can be transported to other workshops or office areas to provide heating for the environment; in the non-heating season, the steam condensation recovery treatment is carried out, and the condensed water can be reused for heat treatment and other workshops to maximize the utilization of energy.

[0021] Preferably, the specific operation of the cooling and slag removal step is as follows: when the return water temperature of the hot stuffing tank is less than 60°C, stop the water supply, and when the return water temperature is less than 50°C, start slag awakening for 1-2 hours. After the hot stuffing is completed, open the stuffing tank cover, use a grab crane to take out the finished steel slag and send it to the finished product warehouse.

[0022] Preferably, the average particle size of the steel slag product is 10-40 mm. More preferably, the content of the steel slag product with a particle size of 20-30 mm exceeds 70%. The steel slag treated by heat and stuffiness is fully pulverized, with a high pulverization rate and a small particle size after pulverization. It does not need to be crushed when used in the building materials industry, eliminating the need for crushing equipment. When there is a need for fine grinding, the smaller particle size can also improve the grinding efficiency and save electricity consumption.

[0023] Preferably, the f-CaO content in the finished steel slag is not more than 3%, the water expansion rate is not more than 2%, and the pulverization rate of the solid steel slag is not less than 90%. 70-97% of the f-CaO and f-MgO in the molten steel slag are dissolved. Compared with the hot stuffy treatment of steel slag in the prior art, the self-decomposition and pulverization of the steel slag in the present invention becomes faster and more thorough, the pulverization rate is higher, the particle size after pulverization is smaller, the water expansion rate of the finished steel slag is also lower, and it shows good volume stability, which is convenient for subsequent resource utilization.

[0024] Preferably, the specific operation of the post-processing step is as follows: the hot-stifled steel slag product is sent to a magnetic separator for magnetic separation treatment by a belt conveyor to meet the application requirements. Steel slag often contains metal elements such as iron. After pulverization, the metal elements are more easily separated and recovered, which improves the metal recovery rate. The metal elements can be recycled, and after the metal elements are removed by magnetic separation treatment, the metal content in the obtained steel slag product is less than 1%, which can meet the application requirements of different fields, such as replacing crushed stone as aggregate of building materials, used for road construction, cement, concrete, house construction, etc.

[0025] The steel slag hot stuffing treatment method provided by the present invention controls the particle size and temperature of the solid steel slag through pretreatment, and controls technical parameters such as water supply, pressure, and treatment time during hot stuffing, so that free calcium oxide (f-CaO) and free magnesium oxide (f-MgO) are fully digested and reacted, and the unstable factors of the steel slag are eliminated. The digestion effect and pulverization effect are stable, and the efficiency and quality of hot stuffing are improved. The whole method has a high automation level and safety factor, and has a significant energy-saving and consumption-reducing effect, a small water consumption, a high waste heat and water resource recovery and reuse rate, and also significantly reduces the production cost.

[0026] The present invention controls the particle size and temperature of solid steel slag through pretreatment, so that the contact area between the steel slag and water is increased, and the temperature can be cooled faster, thereby improving the cooling efficiency; by controlling the pressure during the hot stuffiness period, the reaction rates of f-CaO and f-MgO are kept at a high state, avoiding the inhibition of the hydration reaction due to excessive steam pressure, and the high-temperature steam produced can be recovered and reused to the greatest extent, thereby improving the thermal energy utilization rate; by controlling the total water supply, it can be ensured that the influence of the water content of the steel slag product on the subsequent equipment is within the allowable range, and the pulverization rate of the steel slag is maintained at more than 90%, and the water consumption is reduced.

[0027] After the steel slag product obtained by the present invention is treated by magnetic separation, the slag and iron are fully separated, the metal recovery rate is improved, and the particle size of the steel slag product is uniform, wherein the f-CaO content does not exceed 3%, the water expansion rate is not more than 2%, the stability is good, and it can be directly used without subsequent crushing, and the utilization rate of the steel slag product can reach 100%, which effectively realizes the maximum utilization of resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 A flow chart of a method for hot stuffiness treatment of steel slag provided in one embodiment of the present invention;

[0030] Figure 2 This is a schematic diagram showing the effect of slag hot stuffiness time and particle size on pulverization rate;

[0031] Figure 3 This is a schematic diagram of the effect of water-slag ratio on pulverization rate;

[0032] Figure 4 This is a curve of the change of the water expansion rate of the finished steel slag with the water bath age. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention is clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work also fall within the scope of protection of the present invention.

[0034] The following examples use conventional instruments and equipment in the art. Unless otherwise specified, the test materials and reagents used in the following examples can be obtained from commercial sources, and their specifications are conventional specifications in the art. If no specific techniques or conditions are specified in the following examples, they can be carried out according to the techniques or conditions described in the literature in the art or according to the product instructions.

[0035] It should be noted that, in the present invention and the following embodiments, concentrations, ratios, etc. not otherwise specified are all weight concentrations, weight ratios, etc., "%" means weight percentage, and "parts" means parts by weight, which are common writing habits used by those skilled in the art and are therefore not described in detail in the present invention.

[0036] In a specific embodiment, Figure 1 The process shown in the figure, the method for hot stuffy treatment of steel slag of the present invention comprises the following steps:

[0037] 1) Pretreatment: Pour the molten slag into the slag tank car and send it to the slag treatment workshop. The solid slag formed by cooling is crushed to a particle size of less than 500mm and sent to the slag turning crane.

[0038] Preferably, the particle size of the solid steel slag after the crushing process is ≤300 mm. Preferably, the temperature of the solid steel slag after the crushing process is ≤500°C.

[0039] 2) Slag dumping: Use the slag turning crane to dump the crushed solid steel slag into the hot stuffy tank. When the loading amount of solid steel slag reaches the preset rated capacity, cover the stuffy tank cover and lock the device, and fill it with water to seal it.

[0040] Preferably, the loading amount of solid steel slag is controlled within a range not exceeding 500 mm above the lower edge of the steam pipe of the hot stuffy pool.

[0041] 3) Hot stuffing: Water is sprayed onto the solid slag through the internal nozzle of the hot stuffing pool cover. After the water comes into contact with the solid slag, hot stuffing treatment begins. During the hot stuffing period, the nozzle continuously supplies water, and the water supply pressure is maintained at 0.3-0.4MPa. The pressure in the hot stuffing pool is interlocked to control the pressure to normal pressure, and the steam recovery system is started simultaneously to recover the generated steam.

[0042] Preferably, the heat-stifling treatment time is 4-6 hours. More preferably, the heat-stifling treatment time is 4 hours.

[0043] Preferably, the total water supply during the hot stuffing treatment, calculated as a water-slag ratio, is 1-1.2 m 3 More preferably, the total water supply during the hot stuffing treatment, calculated as water-slag ratio, is 1m 3 / t.

[0044] Preferably, the steam recovery system is connected to a heating system, a high-temperature steam system, or a steam condensation recovery treatment system, and the condensed water produced by the steam condensation recovery treatment system is reused in the water supply system for heat and stuffiness treatment.

[0045] 4) Cooling and slag removal: When the return water temperature of the hot stewing tank is less than 60℃, stop the water supply. When the return water temperature is less than 50℃, start slag awakening for 1-2 hours. After the hot stewing is completed, open the stewing tank cover and use a grab crane to take out the finished steel slag and send it to the finished product warehouse.

[0046] Preferably, the average particle size of the finished steel slag is 10-40 mm. More preferably, the content of the finished steel slag with a particle size of 20-30 mm exceeds 70%.

[0047] Preferably, the f-CaO content in the finished steel slag does not exceed 3%.

[0048] Preferably, the water expansion rate of the finished steel slag product is no more than 2%.

[0049] Preferably, the pulverization rate of the solid steel slag is not less than 90%.

[0050] 5) Post-processing: The hot-stifled steel slag product is sent to the magnetic separator for magnetic separation through a belt conveyor to meet application requirements.

[0051] As an improvement to the aforementioned implementation, water supply is carried out in three stages during the heat-stuffing treatment, while ensuring that the steam pressure in the heat-stuffing pool is stable at normal pressure. The specific operations are as follows: in the first stage, the water supply is 25-35% of the total water supply; in the second stage, the water supply is 45-55% of the total water supply; in the third stage, the water supply is 20-30% of the total water supply.

[0052] Through phased water supply and interlocking control of pressure, the safe production of the hot stuffy pool is ensured, and the reaction of f-CaO and f-MgO in the steel slag with water and steam can be more complete and rapid, making the f-CaO and f-MgO content in the steel slag product lower, further improving the volume stability of the steel slag product, and reducing the consumption of hot stuffy water supply, with obvious energy saving and emission reduction effects. Supplying water in different stages will also lead to a significant phased decrease in the temperature of the steel slag. During the hot stuffy period, a large amount of C2S is formed in the hot stuffy pool. C2S exists in the form of α, β and γ, and can undergo different forms of transformation at different temperatures. Due to the different crystal structures and densities, its internal stress increases, which makes it easy to pulverize the steel slag and improve the pulverization rate.

[0053] In the first stage, the water supply is moderate, which can quickly reduce the temperature of the slag. The high-temperature steam generated in combination with the water supply can first appropriately digest a small portion of f-CaO and f-MgO, so that part of the slag is pulverized into smaller particles, which is convenient for increasing the contact area between the slag and the water in the subsequent stage; in the second stage, the water supply is the highest. At this time, the preliminarily pulverized slag can contact with water over a larger area and react to digest f-CaO and f-MgO, and the elimination speed and elimination rate are also the highest; in the third stage, the water supply is the lowest. At this time, most of the slag has been pulverized, and the remaining small amount of slag is pulverized at this stage. The hydration reaction of the slag in the first two stages can also be further promoted at this stage, making the hydration reaction more complete, so as to ensure that the f-CaO and f-MgO content in the slag can be reduced to a minimum, and at the same time, the pulverized slag can be cooled.

[0054] It should be noted that the heat-stifling tank, crushing equipment, magnetic separation equipment, etc. used in the present invention are all commonly used equipment in the field, and their structures are also commonly used structures in the field, and are not specifically limited, so their specific structures are not described in detail here. Similarly, the specific water spraying method, slag awakening operation, etc. in the present invention are all conventional operations in the field, and are not limited or described in detail here.

[0055] The present invention is further described in detail below in conjunction with the examples. However, it should be understood that the examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0056] In the embodiment, the hot stuffing treatment of the present invention is carried out by taking the steel slag produced in the same batch of a steel plant as an example, wherein the effective volume of the hot stuffing pool is 150m 3 , can process 150t of steel slag at one time. The main components of steel slag are shown in Table 1.

[0057] Table 1 Main components of steel slag (mass percentage / %)

[0058] Main Ingredients CaO <![CDATA[SiO2]]> <![CDATA[Al2O3]]> MgO FeO <![CDATA[P2O5]]> TFe Mass fraction / % 55 12 2 9 8 2 21

[0059] Embodiment 1:

[0060] A method for hot stuffy treatment of steel slag comprises the following steps:

[0061] 1) Pretreatment: Pour the molten slag into the slag tank car and send it to the slag treatment workshop, and crush the solid slag formed by cooling until the particle size is reduced to less than 500mm, and then send the crushed solid slag cooled to below 500℃ into the slag turning vehicle.

[0062] 2) Slag dumping: Use the slag turning crane to dump the crushed solid steel slag into the hot stuffy tank. When the loading amount of solid steel slag reaches the preset rated capacity (the loading amount is controlled within 500mm above the lower edge of the steam pipe of the hot stuffy tank), cover the stuffy tank cover and lock the device, and fill it with water to seal it.

[0063] 3) Hot stuffing: Water is sprayed onto the solid slag through the internal nozzle of the hot stuffing pool cover. After the water contacts the solid slag, hot stuffing treatment begins. During the hot stuffing period, the nozzle continuously supplies water, and the water supply pressure is maintained at 0.3MPa. The pressure in the hot stuffing pool is controlled by interlocking to be normal pressure, and the steam recovery system is started synchronously to recover the generated steam. The hot stuffing treatment time is 4h. The total water supply during the hot stuffing treatment, calculated in terms of water-slag ratio, is 1m 3 / t.

[0064] 4) Cooling and slag removal: When the return water temperature of the hot simmering tank is less than 60℃, stop the water supply. When the return water temperature is less than 50℃, start slag awakening for 1 hour. After the hot simmering is finished, open the simmering tank cover, use a grab crane to take out the steel slag products and send them to the finished product warehouse. The average particle size of the steel slag products is 10-40mm.

[0065] 5) Post-processing: The hot-stifled steel slag product is sent to the magnetic separator for magnetic separation through a belt conveyor to meet application requirements.

[0066] Embodiment 2:

[0067] A method for hot stuffy treatment of steel slag comprises the following steps:

[0068] 1) Pretreatment: Pour the molten slag into the slag tank car and send it to the slag treatment workshop, and crush the solid slag formed by cooling until the particle size is reduced to less than 500mm, and then send the crushed solid slag cooled to below 500℃ into the slag turning vehicle.

[0069] 2) Slag dumping: Use the slag turning crane to dump the crushed solid steel slag into the hot stuffy tank. When the loading amount of solid steel slag reaches the preset rated capacity (the loading amount is controlled within 500mm above the lower edge of the steam pipe of the hot stuffy tank), cover the stuffy tank cover and lock the device, and fill it with water to seal it.

[0070] 3) Hot stuffing: Water is sprayed onto the solid slag through the internal nozzle of the hot stuffing pool cover. After the water contacts the solid slag, hot stuffing treatment begins. During the hot stuffing period, the nozzle continuously supplies water, and the water supply pressure is maintained at 0.4MPa. The pressure in the hot stuffing pool is controlled by interlocking to be normal pressure, and the steam recovery system is started synchronously to recover the generated steam. The hot stuffing treatment time is 6h. The total water supply during the hot stuffing treatment, calculated in terms of water-slag ratio, is 1.2m 3 / t.

[0071] 4) Cooling and slag removal: When the return water temperature of the hot simmering tank is less than 60℃, stop the water supply. When the return water temperature is less than 50℃, start slag awakening for 2 hours. After the hot simmering is over, open the simmering tank cover, use a grab crane to take out the steel slag products and send them to the finished product warehouse. The average particle size of the steel slag products is 10-40mm.

[0072] 5) Post-processing: The hot-stifled steel slag product is sent to the magnetic separator for magnetic separation through a belt conveyor to meet application requirements.

[0073] Embodiment 3:

[0074] A method for hot stuffy treatment of steel slag comprises the following steps:

[0075] 1) Pretreatment: Pour the molten slag into the slag tank car and send it to the slag treatment workshop, and crush the solid slag formed by cooling until the particle size is reduced to less than 500mm, and then send the crushed solid slag cooled to below 500℃ into the slag turning vehicle.

[0076] 2) Slag dumping: Use the slag turning crane to dump the crushed solid steel slag into the hot stuffy tank. When the loading amount of solid steel slag reaches the preset rated capacity (the loading amount is controlled within 500mm above the lower edge of the steam pipe of the hot stuffy tank), cover the stuffy tank cover and lock the device, and fill it with water to seal it.

[0077] 3) Hot stuffing: Water is sprayed onto the solid slag through the internal nozzle of the hot stuffing pool cover. After the water contacts the solid slag, hot stuffing treatment begins. During the hot stuffing period, the nozzle continuously supplies water, and the water supply pressure is maintained at 0.3MPa. The pressure in the hot stuffing pool is controlled by interlocking to be normal pressure, and the steam recovery system is started synchronously to recover the generated steam. The hot stuffing treatment time is 5h. The total water supply during the hot stuffing treatment, calculated in terms of water-slag ratio, is 1.1m 3 / t.

[0078] 4) Cooling and slag removal: When the return water temperature of the hot simmering tank is less than 60℃, stop the water supply. When the return water temperature is less than 50℃, start slag awakening for 1.5 hours. After the hot simmering is over, open the simmering tank cover, use a grab crane to take out the steel slag products and send them to the finished product warehouse. The average particle size of the steel slag products is 10-40mm.

[0079] 5) Post-processing: The hot-stifled steel slag product is sent to the magnetic separator for magnetic separation through a belt conveyor to meet application requirements.

[0080] Test Example 1:

[0081] 1) Setting of heat treatment time

[0082] In this test example, the pulverization rate of steel slag is used as the basis to determine the heat treatment result of steel slag. The pulverization rate is determined by taking equal amounts of solid steel slag at a temperature of 500°C as samples, wherein the particle sizes of the solid steel slag are 500mm and 300mm respectively, and the water-slag ratio is 1m 3 / t, water supply pressure of 0.3MPa, and pressure of normal pressure, heat-stifling treatment was carried out according to the method of the present invention, and the treatment time was 1, 2, 3, 4, 5, and 6h respectively. The obtained steel slag product was dried to constant weight, passed through a 40mm sieve, and the mass of the material on the sieve was weighed. The pulverization rate was calculated using the following formula: pulverization rate K / % = (G-G1) / G×100%, where G is the dry weight of the sample before treatment / g, and G1 is the dry weight of the material on the sieve after heat-stifling treatment / g. Each test case was set up with 3 parallels, and the average value was taken. The results are shown in the figure. Figure 2 shown.

[0083] Figure 2 The figure is a schematic diagram of the effect of hot stuffing time and slag particle size on the pulverization rate. It can be seen from the results in the figure that the hot stuffing time and slag particle size have a significant effect on the pulverization rate. As the hot stuffing time increases, the pulverization rate increases significantly. Among them, when the slag particle size is 300mm, the pulverization rate no longer increases after the hot stuffing time reaches 4h; when the slag particle size is 500mm, the slag needs a longer time to be fully pulverized, and its maximum pulverization rate is also significantly lower than the pulverization rate of 300mm. Therefore, in the actual operation process, the optimal duration of hot stuffing treatment is 4h, and the slag stuffing cycle can match the converter production cycle, and the comprehensive effect is the best. It can be seen that the size of the slag must be controlled before the hot stuffing treatment of the slag. When the proportion of large pieces of slag is high, it is necessary to crush the slag, otherwise it will affect the pulverization rate and water permeability of the slag, resulting in incomplete pulverization of the slag.

[0084] 2) Determination of water-slag ratio

[0085] In this test example, the pulverization rate of steel slag is used as a basis to determine the heat treatment result of steel slag, wherein the pulverization rate is determined by taking equal amounts of solid steel slag at a temperature of 500°C as samples, and heat-stifling for 4 hours according to the method of the present invention under the conditions of a water supply pressure of 0.3MPa and a pressure of normal pressure, wherein the particle sizes of the solid steel slag are 500mm and 300mm, respectively, and the water-slag ratios during the heat-stifling are 0.7, 0.8, 0.9, 1.0, 1.1, 1.2m, respectively. 3 / t, dry the obtained steel slag to constant weight, pass it through a 40mm sieve, and weigh the mass of the material on the sieve. Calculate the powdering rate according to the formula in 1). Each test case has 3 parallels and the average value is taken. The results are shown in Figure 3 shown.

[0086] Figure 3 The effect of water-slag ratio on pulverization rate is shown in the figure. 3 / t, the influence of moisture content of finished steel slag on subsequent equipment is within the allowable range, and the pulverization rate of steel slag with a particle size of 300mm is significantly better than that of steel slag with a particle size of 500mm. The pulverization rate of steel slag is close to 98%, which can fully meet the requirements of subsequent steel slag magnetic separation treatment.

[0087] Embodiment 4:

[0088] The better operating parameters optimized by the above test and data are introduced into the method of the present invention, thereby obtaining a steel slag hot stuffing treatment method, comprising the following steps:

[0089] 1) Pretreatment: Pour the molten slag into the slag tank car and send it to the slag treatment workshop, and crush the solid slag formed by cooling until the particle size is reduced to 300mm, and then send the crushed solid slag cooled to below 500℃ into the slag turning vehicle.

[0090] 2) Slag dumping: Use the slag turning crane to dump the crushed solid steel slag into the hot stuffy tank. When the loading amount of solid steel slag reaches the preset rated capacity (the loading amount is controlled within 500mm above the lower edge of the steam pipe of the hot stuffy tank), cover the stuffy tank cover and lock the device, and fill it with water to seal it.

[0091] 3) Hot stuffing: Water is sprayed onto the solid slag through the internal nozzle of the hot stuffing pool cover. After the water contacts the solid slag, hot stuffing treatment begins. During the hot stuffing period, the nozzle continuously supplies water, and the water supply pressure is maintained at 0.3MPa. The pressure in the hot stuffing pool is controlled by interlocking to be normal pressure, and the steam recovery system is started synchronously to recover the generated steam. The hot stuffing treatment time is 4h. The total water supply during the hot stuffing treatment, calculated in terms of water-slag ratio, is 1m 3 / t.

[0092] 4) Cooling and slag removal: When the return water temperature of the hot simmering tank is less than 60℃, stop the water supply. When the return water temperature is less than 50℃, start the slag awakening for 1.5 hours. After the hot simmering is finished, open the simmering tank cover, use the grab crane to take out the steel slag products and send them to the finished product warehouse. The average particle size of the steel slag products is 10-40mm, of which the content of steel slag products with a particle size of 20-30mm exceeds 70%.

[0093] 5) Post-processing: The hot-stifled steel slag product is sent to the magnetic separator for magnetic separation through a belt conveyor to meet application requirements.

[0094] The main components of the steel slag product after being treated by the hot stuffing treatment method of this embodiment are shown in Table 2.

[0095] Table 2 Main components of steel slag finished product (mass percentage / %)

[0096] Main Ingredients CaO <![CDATA[SiO2]]> <![CDATA[Al2O3]]> MgO FeO <![CDATA[P2O5]]> TFe Mass fraction / % 39 10 2 7 6 1.9 20.7

[0097] It can be seen from the above table that after the steel slag is treated with heat and stuffing, the content of CaO and MgO in it is significantly reduced. They are eliminated during the heat and stuffing process, which enhances the stability of the steel slag product.

[0098] Embodiment 5:

[0099] A method for hot stuffy treatment of steel slag, based on embodiment 4, further comprising:

[0100] In step 3), during the heat treatment, water supply is carried out in three stages, while ensuring that the pressure in the heat treatment tank is normal pressure. The total water supply, calculated in terms of water-slag ratio, is 1m3 / t, the specific operation is as follows: in the first stage, the water supply is 30% of the total water supply; in the second stage, the water supply is 50% of the total water supply; in the third stage, the water supply is 20% of the total water supply.

[0101] The main components of the steel slag product after being treated by the hot stuffing treatment method of this embodiment are shown in Table 3.

[0102] Table 3 Main components of steel slag finished product (mass percentage / %)

[0103] Main Ingredients CaO <![CDATA[SiO2]]> <![CDATA[Al2O3]]> MgO FeO <![CDATA[P2O5]]> TFe Mass fraction / % 37 7 1.8 6 5 1.5 20

[0104] From the comparison of the data in the above table with the data in Example 4, it can be seen that the phased water supply method during the hot stuffing treatment can make the f-CaO and f-MgO in the steel slag react with water and steam more fully and quickly, so that the CaO and MgO content in the steel slag product is lower, and the volume stability of the steel slag product is further improved.

[0105] Comparative Example 1:

[0106] A method for hot stuffy treatment of steel slag, which differs from Example 4 only in that:

[0107] In step 1), the solid steel slag is crushed until the particle size is reduced to 800 mm.

[0108] Comparative Example 2:

[0109] A method for hot stuffy treatment of steel slag, which differs from Example 4 only in that:

[0110] In step 3), the steam pressure in the heat-stifling tank during the heat-stifling treatment is stabilized at 200.0 kPa.

[0111] Comparative Example 3:

[0112] A method for hot stuffy treatment of steel slag, which differs from Example 4 only in that:

[0113] In step 3), the total water supply during the hot stuffing treatment, calculated as water-slag ratio, is 1.5m 3 / t.

[0114] Test Example 2:

[0115] Determination of powdering rate and f-CaO content

[0116] Determination method: Take the steel slag and steel slag products before and after heat treatment in Example 4, Example 5 and Comparative Examples 1-3 in equal amounts as samples, and use the water-slag ratio of 0.4m / s in 2) of Test Example 1 as the test sample. 3The heat treatment method of / t is comparative example 4. The slag pulverization rate is determined according to the method in 2) of test example 1. At the same time, the f-CaO content in the finished slag is determined, specifically by the glycerol-anhydrous ethanol chemical titration method, and the f-CaO content is f1=(T CaO ×V) / (G×1000)×100%, where: T CaO is the milliliters of CaO equivalent to each milliliter of benzoic acid in mg / ml, V is the total milliliters of benzoic acid anhydrous ethanol solution consumed during titration, and G is the weight of the sample in g. Each test example is set up with 3 parallels, and the average value is taken. The results are shown in Table 4.

[0117] Table 4 Powdering rate and f-CaO content determination results (unit: %)

[0118] Example 4 Example 5 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Powdering rate 97.9 98.7 87.6 91.2 90.3 92.6 f-CaO content 2.56 1.04 5.06 6.74 5.33 5.86

[0119] As can be seen from the results in the above table, the optimization measures in Example 5 can further improve the pulverization rate of steel slag and reduce the f-CaO content in the finished steel slag, the degree of f-CaO digestion is higher, and the stability of the steel slag product is better. Compared with other comparative examples, the pulverization rate in Example 4 is reduced to varying degrees, and the f-CaO content is also higher than that in Example 4, indicating that the particle size of steel slag, the pressure during the hot stuffy period, and the water-slag ratio have different degrees of influence on the pulverization rate of steel slag and the digestion of f-CaO, while the operating parameters of the present invention show a higher pulverization rate and a lower f-CaO content. Under the premise of ensuring the quality of the finished steel slag, it has a lower pressure, so that the amount of recoverable steam is large, the heat utilization rate is high, and the water consumption is small, which saves water resources, and has suitable crushing particle size requirements, saves the energy consumption of crushing equipment, and has more practical and promotion value.

[0120] Test Example 3:

[0121] Determination of water swelling rate

[0122] Determination method: Take the same amount of steel slag products after heat treatment in Example 4, Example 5 and Comparative Examples 1-3 as samples, and use the water-slag ratio of 0.4m in 2) of Test Example 1 as the test sample. 3 The heat treatment method of / t is comparative example 4. The water swelling rate is determined according to the method in GB / T24175-2009, and the water swelling rate is γ=(d i -d0) / d0×100%, where: d0 is the initial reading of the dial indicator (mm), d i is the reading of the dial gauge after immersion in water (mm). Each test case has 3 parallels and the average value is taken. Figure 4 shown.

[0123] Figure 4The graph is a curve of the change of the water expansion rate of the steel slag product with the water bath age. It can be seen from the results that the water expansion rate of the steel slag product treated by the optimization measures in Example 5 is stable and lower than the water expansion rate of Example 4. When the water bath age is 10 days, its water expansion rate is only 0.7%, which is significantly lower than 1.1% of Example 4, and its volume stability is higher. Compared with other comparative examples, Example 4 is in a steady and slightly increasing trend, while other comparative examples show a larger expansion rate in the early stage, that is, as the water bath age increases, the increase in the water expansion rate is first large and then small and finally tends to a higher value. When the water bath age is 10d, the water expansion rates are: Comparative Example 1 is 4.3%, Comparative Example 2 is 3.7%, Comparative Example 3 is 2.3%, and Comparative Example 4 is 3.1%, all of which exceed 2%, which does not meet the technical index requirements for the application of steel slag in asphalt concrete in DB42 / T1125-2015 "Technical Specifications for Steel Slag Aggregates for Asphalt Concrete", and its use is limited. Therefore, the steel slag finished product obtained by the method of the present invention has a wider range of use and application.

[0124] It should be noted that in the present invention, the detailed steps of some operations are not described in detail, but belong to the prior art known to those skilled in the art, so they will not be repeated here. In addition, in the present invention, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are only for simplicity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be deemed to have covered and specifically disclosed all possible secondary ranges and individual values ​​(including integers and fractions) within the range.

[0125] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. In the present invention, not all possible combinations of the various technical features in the various embodiments or embodiments are described. As long as there is no contradiction in the combination of these technical features, the various technical features in the various embodiments or embodiments can be arbitrarily combined, and all possible combinations should be considered to be within the scope of this specification. Although the present invention has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments can still be modified, or some or all of the technical features therein can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for hot stuffing treatment of steel slag, characterized in that: include: The pre-treatment step comprises the steps of cooling and crushing the molten steel slag to obtain solid steel slag; sending the solid steel slag into a hot stuffing tank to discharge the slag; hot stuffing the solid steel slag in the hot stuffing tank to heat stuffing; sending the finished steel slag obtained after hot stuffing into a finished product bin to cool and discharge the slag; and the post-treatment step of magnetic separation treatment of the finished steel slag; In the pretreatment step, the solid slag obtained has a particle size of ≤500 mm and a temperature of ≤500° C.; In the heat-stuffing step, the total water supply during the heat-stuffing treatment, calculated as a water-slag ratio, is 1-1.2m 3 / t; the pressure in the hot and stuffy pool is normal pressure.

2. The method for hot stuffing treatment of steel slag according to claim 1, characterized in that: The specific operation of the pretreatment step is as follows: pouring the molten slag into a slag tank car and sending it to a slag treatment workshop, and crushing the solid slag formed by cooling until the particle size is reduced to less than 500mm, and sending it to a slag turning vehicle.

3. The method for hot stuffing treatment of steel slag according to claim 2, characterized in that: The particle size of the solid steel slag after the crushing process is ≤300mm.

4. The method for hot stuffing treatment of steel slag according to claim 1, characterized in that: The specific operation of the heat-stuffing step is as follows: water is sprayed onto the solid steel slag through the internal nozzle of the heat-stuffing pool cover, and the heat-stuffing treatment begins after the water contacts the solid steel slag. During the heat-stuffing period, the nozzle continuously supplies water, and the steam recovery system is simultaneously started to recover the generated steam.

5. The method for hot stuffing treatment of steel slag according to claim 4, characterized in that: During the heat and stuffiness period, the water supply pressure of the nozzle is maintained at 0.3-0.4MPa, and the pressure in the heat and stuffiness pool is controlled by interlocking to be normal pressure.

6. The method for hot stuffing treatment of steel slag according to claim 1, characterized in that: The heat treatment time is 4-6 hours.

7. The method for hot-stifling treatment of steel slag according to claim 4, characterized in that: The steam recovery system is connected to a heating system, a high-temperature steam system, or a steam condensation recovery treatment system, and the condensed water generated by the steam condensation recovery treatment system is reused in the water supply system for heat and stuffiness treatment.

8. The method for hot stuffing treatment of steel slag according to claim 1, characterized in that: The specific operation of the cooling and slag removal step is as follows: when the return water temperature of the hot stuffing tank is less than 60°C, stop the water supply, and when the return water temperature is less than 50°C, start slag awakening for 1-2 hours. After the hot stuffing is completed, open the stuffing tank cover, use a grab crane to take out the finished steel slag and send it to the finished product warehouse.

9. The method for hot stuffing treatment of steel slag according to any one of claims 1 to 8, characterized in that: The average particle size of the finished steel slag product is 10-40 mm.

10. The steel slag hot stuffing treatment method according to claim 9, characterized in that: The f-CaO content in the finished steel slag is no more than 3%, the water expansion rate is no more than 2%, and the pulverization rate of the solid steel slag is no less than 90%.

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