CN116751909A - A resource utilization method of steel slag and coal gangue - Google Patents

Abstract

The application provides a resource utilization method of steel slag and coal gangue. It comprises the following steps: s1, providing mixed slag of steel slag, coal gangue and reducing agent; s2, roasting the mixed slag at 1450-1550 ℃ to obtain slag liquid and metal iron liquid; s3, carrying out water quenching on the slag liquid to obtain active micro powder; and (5) treating the molten metal to obtain pig iron. The application solves the problems that the steel slag and the gangue are not fully utilized in resource, valuable metal iron in the steel slag can not be fully recovered, and the cost of adding auxiliary materials is high in the prior art.

Description

A resource utilization method of steel slag and coal gangue

Technical field

The present invention relates to the technical field of solid waste disposal and resource utilization, and specifically, to a resource utilization method of steel slag and coal gangue.

Background technique

With the development of industry, the stock of solid waste such as steel slag and coal gangue is increasing year by year, which has become a major environmental problem. There are currently more and more research efforts devoted to recovering the available components in these solid wastes.

Coal gangue is one of the solid wastes currently accumulated in large quantities. Depending on the type of raw coal and processing technology, the carbon content in coal gangue generally ranges from 5 to 15%. Therefore, coal gangue cannot be directly used for power generation, making it difficult to realize resource utilization, which will cause serious energy waste and ecological damage. But, on the other hand, the carbon in coal gangue can be used as a low-cost reducing agent to turn waste into treasure.

Steel slag is also a large amount of solid waste, which occupies a large amount of land resources and causes environmental pollution. Metal elements such as iron and manganese contained in steel slag will also produce harmful gases or liquids during long-term storage, causing pollution to soil, water sources and air. In addition, steel slag also contains a large amount of calcium oxide, so the stability of steel slag is not good, which makes the transportation of steel slag a safety hazard, and also limits the direct large-scale utilization of steel slag. If steel slag can be utilized as a resource and converted into valuable materials, it will not only reduce raw material consumption and energy consumption, but also reduce the negative impact on the environment. Therefore, it is of great significance to realize the resource utilization of steel slag.

Furthermore, if coal gangue can be used as a reducing agent to recover iron from steel slag, the resource utilization of these two solid wastes can be achieved with one stone, which has good economic and environmental benefits and can be widely used in industrialization. has good prospects.

There are already some resource utilization methods of steel slag in the existing technology.

For example, patent CN114774609A discloses a resource utilization method of vanadium-containing steel slag, aiming to solve the problem of low resource utilization rate of vanadium-containing steel slag in existing methods. According to the characteristics of vanadium-containing steel slag, the vanadium-containing steel slag is tempered by adding silicon raw materials, so that the molten slag after water quenching can form a calcium silicate glassy substance, which can be used as highly active slag powder after grinding. The resource utilization rate and added value of vanadium-containing steel slag are improved. However, in this method, the siliceous raw material is added with silica containing _SiO2 content >80%, and the added amount is 15-25%. In addition, this method also adds 5 to 15% anthracite and 3 to 5% fluorspar, which is relatively expensive.

Patent CN115301716A heats red mud, fly ash, steel slag, and coal gangue industrial solid waste to 1800-2400°C, then adds Na ₂ CO ₃ , O ₂ and reducing agent to react, and separates molten iron and liquid slag water; liquid slag water Add sodium salt to react at 30-300°C to obtain a reaction liquid and sediment; pass the reaction liquid into a calcium salt precipitation tank, an aluminum salt precipitation tank, and a silicate tank in sequence, and pass in CO ₂ respectively for acidification reaction. After filtration, calcium salt is obtained in turn. salt, aluminum salt, silicic acid and alkali solution; concentrate and crystallize the alkali solution to obtain potassium salt and sodium salt; dry the sediment and heat it to 600-1300°C and pass in Cl ₂ to react to obtain gaseous TiCl ₄ and residue; the residue Add sodium hydroxide and react to obtain magnesium hydroxide. The heating temperature of this invention is too high, the energy consumption is large and the process is relatively complex, and the iron elements in the slag are not recycled.

Patent CN114134276B, mix red mud, carbon powder or coke powder, and magnetically separated iron powder to form a pretreatment powder; add a binder to the pretreatment powder to make a pretreatment cue ball; pour liquid steel slag into the collision unit, and pretreat the powder. The processed material collides with the fluid steel slag obliquely upward to form sandwich balls; the solidified sandwich balls are screened into recycled powder and coarse particles by rotary stirring; the coarse particles are ground to form crushed powder; the recycled powder and crushed powder are The iron powder selected by the magnet is reused or used as finished iron materials; the non-magnetic recycled powder and crushed powder are used as cementitious materials or cement additives. The process of this invention is relatively complex and requires a high-cost binder. In addition, the dosage of steel slag is only 10%, which is not conducive to the realization of large-scale consumption of steel slag.

Generally speaking, in the existing technology, there are problems such as high heating temperature, large energy consumption and inability to recover the iron resources in the slag, or the raw materials added in the process that can realize the recovery of iron resources are industrial raw materials and the ratio is large. The cost is high, or the process of recovering iron from steel slag using solid waste as the main material has a low proportion of steel slag and the process is relatively complicated. It does not realize the comprehensive utilization of large quantities of steel slag and other problems, which is not conducive to industrial promotion.

In view of this, it is necessary to provide a resource utilization method of coal gangue and steel slag that has high steel slag utilization rate, can fully recover valuable metal iron, and is low-cost.

Contents of the invention

The main purpose of the present invention is to provide a resource utilization method of steel slag and coal gangue to solve the problem that in the existing technology, steel slag and coal gangue are not fully utilized as resources, and the valuable metal iron in the steel slag cannot be fully recovered and auxiliary materials are added. The problem is the high cost of industrial raw materials.

In order to achieve the above object, according to one aspect of the present invention, a resource utilization method of steel slag and coal gangue is provided, which includes: S1, providing mixed slag material of steel slag, coal gangue and reducing agent; S2, mixing the mixed slag material Roasting is performed at 1450-1550°C to obtain slag liquid and molten metal; in S3, the slag liquid is quenched with water to obtain active micropowder; the molten metal is processed to obtain pig iron material.

Further, the temperature of the roasting treatment is 1450-1500°C, and the roasting time is 20-80 minutes; the preferred roasting time is 20-40 minutes.

Further, the weight percentage of steel slag in the mixed slag material is ≥75%.

Further, the weight ratio of steel slag to coal gangue is (75~85): (10~20).

Further, the weight ratio of steel slag and coal gangue is (78~83): (12~18).

Further, the weight ratio of reducing agent to steel slag is (3~5):(75~85), preferably (4~5):(75~85); more preferably, the reducing agent is anthracite, coke, or graphite. of one or more.

Further, the average particle size of the mixed slag material is <5 mm; preferably, the particle size of the mixed slag material is 80 μm and the sieve residue is ≤15%.

Further, after obtaining the liquid slag and the molten metal, step S2 also includes: pouring the liquid slag and the molten metal into a slag bag for heat preservation.

Further, before the roasting process, step S2 also includes: a temperature-raising stage of heating the mixed slag material, and the temperature-raising rate is 5-20°C/min.

Further, before step S2, stir the mixed slag material for 20 to 30 minutes.

By applying the technical solution of the present invention, a resource utilization method of steel slag and coal gangue is provided. The raw materials of the present invention are mainly solid waste steel slag and coal gangue that are currently stored in large amounts, and active micropowder is recovered. The iron content in the hot metal produced is more than 90%, and the iron content in the tailings is reduced to less than 1%. The iron recovery rate in the invention reaches more than 90%, the production process is simple, the raw material cost is low, the method has good economic and environmental benefits, and is suitable for large-scale promotion and application in industry. In addition, the present invention has a lower roasting temperature and less energy consumption, further saving costs.

Detailed ways

It should be noted that, as long as there is no conflict, the embodiments and features in the embodiments of this application can be combined with each other. The present invention will be described in detail below with reference to examples.

In order to solve the problems in the prior art as mentioned above, the present invention provides a resource utilization method of steel slag and coal gangue, which includes: S1, providing mixed slag material of steel slag, coal gangue and reducing agent; S2, The mixed slag is roasted at 1450-1550°C to obtain liquid slag and molten metal; in S3, the liquid slag is quenched with water to obtain active micropowder; and the molten metal is processed to obtain pig iron.

The raw materials of the present invention are mainly solid waste steel slag and coal gangue that are currently stored in large quantities. Since steel slag contains a large amount of calcium oxide and has poor stability, it cannot be directly utilized in large quantities. However, existing steel slag also contains A large amount of iron oxide content causes a waste of iron resources. Due to its relatively low carbon content, coal gangue cannot be directly used for power generation, resulting in a large accumulation of coal gangue, which will cause serious energy waste and ecological damage. Using the carbon in the gangue to reduce the iron oxide in the steel slag can not only achieve efficient utilization of carbon resources, but also realize resource recovery of iron. At the same time, the by-product active micron powder is prepared, and at the same time, it can reduce the bulk of solid waste steel slag and coal gangue. emissions, achieving the goal of “treating waste with waste and turning waste into treasure”. The iron content in the pig iron prepared by the invention is more than 90%, the iron content in the tailings is reduced to less than 1%, the iron recovery rate reaches more than 90%, the production process is simple, the raw material cost is low, and it has good economic benefits and environmental benefits Benefits, suitable for large-scale promotion and application in industry. In addition, the present invention has a lower roasting temperature and less energy consumption, further saving costs.

In a typical embodiment of the present invention, the main components of steel slag may include: CaO 35-40wt%, Fe ₂ O ₃ 18-25wt%, SiO ₂ 15-20wt%, Al ₂ O ₃ 5-10wt% , MgO 5~10wt%; the carbon content of coal gangue can include: 8~12wt%, and its main components measured after roasting to remove carbon can include: SiO ₂ 52~60wt%, Al ₂ O ₃ 25~30wt%, Fe ₂ O ₃ 6～10wt%, CaO 1～5wt%. The above-mentioned steel slag and coal gangue may each contain a small amount of other impurities. The content of these impurities is low and their impact on the process of the present invention is negligible, so they will not be described again.

In the present invention, the physical phase of the generated water quenching slag is mainly a glass phase, which can be made into active micropowder after grinding, which is a value-added product that can replace cement and other products.

In the present invention, the roasting process in step S2 does not need to be carried out under the protection of an inert atmosphere. This is because during the roasting process, the steel slag melts as a liquid phase; and the carbon in the gangue will first participate in the iron. The reduction reaction of the oxide generates carbon monoxide gas, which continues to participate in the reduction reaction and is consumed to obtain carbon dioxide gas; in this way, carbon monoxide and carbon dioxide gas maintain a dynamic balance in the reaction environment. Therefore, in the process of the present invention, a large amount of recovered iron will not be oxidized. Not adding additional inert gas is also due to considerations of actual equipment cost and process complexity. Moreover, additional addition of inert gas will also reduce the concentration of reducing gas in the reaction system, so it may have a negative impact on the recovery rate of the product.

In order to better recover iron, in a preferred embodiment, the temperature of the roasting treatment is 1450-1500°C, and the roasting time is 20-80 minutes; the preferred roasting time is 20-40 minutes. The above-mentioned further preferred roasting treatment conditions can further save energy consumption on the basis of ensuring the good fluidity of the obtained slag liquid and molten metal.

In a preferred embodiment, the steel slag accounts for ≥75% by weight of the mixed slag material. In some embodiments, the present invention can realize the recovery of iron resources in bulk solid waste steel slag, and has good economic value.

In a preferred embodiment, the weight ratio of steel slag to coal gangue is (75-85): (10-20). Steel slag is mainly composed of oxides of calcium, iron, silicon, aluminum, magnesium and a small amount of manganese, phosphorus, etc. The main mineral phases are solid solutions formed by dicalcium silicate, tricalcium silicate, calcium aluminoferrite and oxides of silicon, magnesium, iron, manganese and phosphorus. It also contains a small amount of free calcium oxide, metallic iron, fluorine and phosphorus. Greystone etc. The main components of coal gangue are silicon dioxide, aluminum oxide and carbon. It also contains iron oxide, calcium oxide, magnesium oxide, sodium oxide, potassium oxide, phosphorus pentoxide, sulfur and trace rare elements. By adjusting the above-mentioned preferred ratio, the present invention can make the mixed slag of the present invention have a suitable binary alkalinity (mCaO/mSiO ₂ , where m represents the weight). The slag with this alkalinity has a similar composition to that of blast furnace slag. After quenching, drying and grinding can be directly prepared into active micro powder, which can be used in the construction industry instead of cement. During the roasting process, appropriate alkalinity is beneficial to the fluidity of the slag liquid and the reduction of energy consumption, and will also increase the service life of the furnace.

In the present invention, the binary alkalinity of the mixed slag material is controlled between 0.8 and 1.2.

For the purpose of further adjusting the alkalinity, the weight ratio of steel slag and coal gangue is preferably (78-83): (12-18).

In the ingredients of the present invention, since the carbon contained in the coal gangue can act as a partial reducing agent, the amount of additional reducing agent that needs to be added can be reduced compared with the existing process. In a preferred embodiment, the weight ratio of the reducing agent to the steel slag is (3-5): (75-85), preferably (4-5): (75-85); more preferably, the reducing agent is One or more of anthracite, coke, and graphite. According to such a proportion, the present invention can further save costs on the basis of achieving sufficient reduction. For the purpose of economic cost and speeding up the reaction rate, anthracite coal is preferably used as the reducing agent.

In order to make the various components in the mixed slag material mix more uniformly, in a preferred embodiment, the average particle size of the mixed slag material is <5mm; preferably, the particle size of the mixed slag material is 80 μm and the sieve residue is ≤15wt% (by weight). count). In actual operations, the process of refining solid waste can be achieved using jaw crushers and ball mills. The ball milling time is 30 to 40 minutes, or a longer treatment process is used to obtain slag with a higher specific surface area. When the particle size is smaller, the components in the mixed slag can be fully contacted and mixed evenly, which is beneficial to improving the iron recovery rate.

In order to maintain the fluidity of the slag liquid and the molten metal iron, which is more conducive to subsequent operations, in a preferred embodiment, after obtaining the slag liquid and the molten metal iron, step S2 also includes: combining the slag liquid and the molten metal iron Pour separately into slag bags to keep warm.

In a preferred embodiment, before the roasting process, step S2 further includes: a temperature-raising stage of heating the mixed slag material, and the temperature-raising rate is 5-20°C/min. Through such a preferred heating stage, the temperature of the material can be made more uniform, which is more conducive to the roasting process.

In order to fully mix the components in the mixed slag material, in a preferred embodiment, before step S2, the mixed slag material is stirred for 20 to 30 minutes.

The present application will be described in further detail below with reference to specific examples. These examples shall not be construed as limiting the scope of protection claimed by the present application.

Unless otherwise specified, in the following examples and comparative examples, the particle size of the mixed slag material is 80 μm sieve residue ≤ 15%.

Unless otherwise specified, in the following _examples and comparative examples, the main components of the steel slag selected include: CaO38.36wt%, _Fe2O321.43wt % _{, SiO217.45wt%, Al2O35.61wt % ,} MgO5.69 wt%, and the balance of other impurities; in the following examples and comparative examples, the carbon content of the selected coal gangue is 11.86wt%. After roasting to remove carbon, the composition and content of the coal gangue were measured. The result is: SiO ₂ 54.22wt%, Al ₂ O ₃ 27.98wt%, Fe ₂ O ₃ 9.14wt%, CaO 2.63wt%, and the balance of other impurities. During the implementation process, the purpose of roasting to remove carbon is to determine the composition and content of coal gangue. In the actual resource utilization process of steel slag and coal gangue involved in the present invention, unroasted coal gangue containing a certain carbon content should be used. . It is easy for those skilled in the art to know that there may be differences in the components and content of steel slag and coal gangue of different types, or of the same type but in different batches; and, for the same batch of steel slag or coal gangue, the composition content of the steel slag or coal gangue may vary. Test results may also vary depending on factors such as sampling location. Therefore, the above values only represent the results of this batch of steel slag and coal gangue in this test.

Example 1

After grinding the steel slag, coal gangue and anthracite, the three are evenly mixed in a ratio of 84:12:4;

Put the mixed slag material into the mixer and stir for 20 minutes to make all materials evenly mixed;

Send the mixed materials into the electric furnace, raise the furnace temperature to 1500°C at a heating rate of 10°C/min, and after keeping it warm for 60 minutes, pour the generated slag liquid and metal liquid into the corresponding slag bags respectively, and wait for cooling After treatment, the components of the produced metal blocks and tailings were analyzed respectively, and the Fe content of the iron blocks was 94.86%, which can be used as high-quality pig iron material. The Fe content in the slag was 0.86%, and the iron element in the original steel slag was 93.90%. It is extracted and recycled into pig iron.

Example 2

After grinding steel slag, coal gangue and anthracite, mix the three evenly in a ratio of 77:18:5;

Put the mixed slag material into the mixer and stir for 25 minutes to make all materials evenly mixed;

Send the mixed materials into the electric furnace, raise the furnace temperature to 1500°C at a heating rate of 10°C/min, and after keeping it warm for 40 minutes, pour the generated slag liquid and metal liquid into the corresponding slag bags respectively, and wait for cooling After treatment, the components of the produced metal blocks and tailings were analyzed respectively, and the Fe content of the iron blocks was 91.68%, which can be used as high-quality pig iron material. The Fe content in the slag was 0.24%, and the iron element in the original steel slag was 95.66%. It is extracted and recycled into pig iron.

Example 3

After grinding steel slag, coal gangue and anthracite, mix the three evenly in a ratio of 76:20:4;

Put the mixed slag material into the mixer and stir for 30 minutes to make all materials evenly mixed;

Send the mixed materials into the electric furnace, raise the furnace temperature to 1500°C at a heating rate of 10°C/min, and after keeping it warm for 60 minutes, pour the generated slag liquid and metal liquid into the corresponding slag bags respectively, and wait for cooling After treatment, the components of the produced metal blocks and tailings were analyzed respectively, and the Fe content of the iron blocks was 98.47%, which can be used as high-quality pig iron material. The Fe content in the slag was 0.84%, and the iron element in the original steel slag was 95.86%. It is extracted and recycled into pig iron.

Example 4

After grinding steel slag, coal gangue and anthracite, mix the three evenly in a ratio of 82:15:3;

Put the mixed slag material into the mixer and stir for 20 minutes to make all materials evenly mixed;

Send the mixed materials into the electric furnace, raise the furnace temperature to 1450°C at a heating rate of 10°C/min, and after keeping it warm for 60 minutes, pour the generated slag liquid and metal liquid into the corresponding slag bags respectively, and wait for cooling After treatment, the components of the produced metal blocks and tailings were analyzed respectively, and the Fe content of the iron blocks was 94.94%, which can be used as high-quality pig iron material. The Fe content in the slag was 0.85%, and the iron element in the original steel slag was 95.38%. It is extracted and recycled into pig iron.

Example 5

After grinding steel slag, coal gangue and anthracite, mix the three evenly in a ratio of 82:14:4;

Put the mixed slag material into the mixer and stir for 25 minutes to make all materials evenly mixed;

Send the mixed materials into the electric furnace, raise the furnace temperature to 1450°C at a heating rate of 10°C/min, and after maintaining the temperature for 40 minutes, pour the generated slag liquid and metal liquid into the corresponding slag bags respectively, and wait for cooling After treatment, the components of the produced metal blocks and tailings were analyzed respectively, and the Fe content of the iron blocks was 91.56%, which can be used as high-quality pig iron material. The Fe content in the slag was 0.55%, and the iron element in the original steel slag was 96.58%. It is extracted and recycled into pig iron.

Example 6

After grinding steel slag, coal gangue and anthracite, mix the three evenly in a ratio of 80:15:5;

Put the mixed slag material into the mixer and stir for 20 minutes to make all materials evenly mixed;

Send the mixed materials into the electric furnace, raise the furnace temperature to 1450°C at a heating rate of 10°C/min, and after keeping it warm for 20 minutes, pour the generated slag liquid and metal liquid into the corresponding slag bags respectively, and wait for cooling After treatment, the components of the produced metal block and tailing slag were analyzed respectively, and the Fe content of the iron block was 92.46%, which can be used as high-quality pig iron material. The Fe content in the slag was 0.14%, and the iron element in the original steel slag was 97.64%. It is extracted and recycled into pig iron.

Example 7

The difference from Example 6 is that the weight ratio of steel slag, coal gangue and anthracite is 90:10:5. The Fe content of the obtained iron block is 86.58%, which cannot be used as high-quality pig iron material. The Fe content in the slag is 1.86%. 87.69% of the iron element in the original steel slag is extracted and recycled into the pig iron material.

Example 8

The difference from Example 6 is that the weight ratio of steel slag, coal gangue and anthracite is 70:30:3. The Fe content of the obtained iron block is 87.89%, which cannot be used as high-quality pig iron material. The Fe content in the slag is 1.90%. 86.97% of the iron element in the original steel slag is extracted and recycled into the pig iron material.

Example 9

The difference from Example 6 is that equal weight of coke is used as the reducing agent. The Fe content of the obtained iron block is 90.68%, which can be used as high-quality pig iron material. The Fe content in the slag is 0.86%. 91.68% of the iron element in the original steel slag is extracted and recycled into the pig iron material.

Comparative example 1

The difference from Example 6 is that coal gangue is not used, and the weight ratio of steel slag to anthracite is 84:16. Within the same temperature range, the Fe content of the obtained iron block was 84.68%, which cannot be used as high-quality pig iron material. The Fe content in the slag was 11.71%. 26.53% of the iron element in the original steel slag was extracted and recycled into the pig iron material.

Comparative example 2

The difference from Example 6 is that the calcination temperature is 1350°C. The Fe content of the obtained iron block is 57.18%, which cannot be used as high-quality pig iron material. The Fe content in the slag is 11.14%. Only 22.66% of the iron element in the original steel slag is extracted and recycled into the pig iron material.

From the above description, it can be seen that the above-mentioned embodiments of the present invention achieve the following technical effects:

The present invention makes full use of steel slag and coal gangue, two types of industrial solid waste that are currently abundant in stockpiles, to extract iron from the scrap steel slag. The process is simple and the prepared pig iron blocks can be directly used in the steel industry, with good economic benefits and good performance. application prospects.

The above descriptions are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims (10)

1. A method for recycling steel slag and coal gangue is characterized by comprising the following steps:

s1, providing mixed slag of steel slag, coal gangue and reducing agent;

s2, roasting the mixed slag at 1450-1550 ℃ to obtain slag liquid and metal iron liquid;

s3, carrying out water quenching on the slag liquid to obtain active micro powder; and treating the molten metal to obtain pig iron.

2. The method for recycling steel slag and coal gangue according to claim 1, wherein the roasting temperature is 1450-1500 ℃ and the roasting time is 20-80 min; preferably, the calcination time is 20 to 40 minutes.

3. The method for recycling steel slag and coal gangue according to claim 1 or 2, wherein the steel slag accounts for more than or equal to 75% of the mixed slag by weight.

4. The method for recycling steel slag and gangue as claimed in any one of claims 1 to 3, wherein the weight ratio of the steel slag to the gangue is (75-85): (10-20).

5. The method for recycling steel slag and gangue according to claim 4, wherein the weight ratio of the steel slag to the gangue is (78-83): (12-18).

6. The method for recycling steel slag and gangue according to any one of claims 1 to 5, wherein the weight ratio of the reducing agent to the steel slag is (3-5): (75-85), preferably (4-5): (75-85); more preferably, the reducing agent is one or more of anthracite, coke, and graphite.

7. The method for recycling steel slag and gangue according to any one of claims 1 to 6, wherein the average particle size of the mixed slag is < 5mm; preferably, the particle size of the mixed slag is 80 mu m and the screen residue is less than or equal to 15 percent.

8. The method for recycling steel slag and gangue as claimed in any one of claims 1 to 7, wherein after obtaining the slag liquid and the molten metal, the step S2 further comprises: and pouring the slag liquid and the metal iron liquid into a slag ladle respectively for heat preservation.

9. The method for recycling steel slag and gangue as claimed in any one of claims 1 to 8, wherein the step S2 further comprises, prior to the roasting treatment: and (3) carrying out a heating stage of heating the mixed slag, wherein the heating rate is 5-20 ℃/min.

10. The method for recycling steel slag and gangue according to any one of claims 1 to 9, wherein the mixed slag is stirred for 20 to 30min before the step S2.