High-added-value utilization method of KR desulfurization slag tailings and desulfurizer

Abstract

The invention discloses a high-added-value utilization method of KR desulfurization slag tailings and a desulfurizing agent. The method comprises the following steps: drying, grinding and screening the KR desulfurization slag tailings subjected to magnetic separation, and collecting screen underflow; the method comprises the following steps: grinding and screening the industrial by-product of titanium dioxide, and collecting screen underflow; the method comprises the following steps: mixing KR desulfurization residues and tailings with industrial by-products of titanium dioxide, adding deionized water, stirring, continuously introducing air in the stirring process until a muddy mixture is formed, and placing the muddy mixture in a storage yard for natural aging to obtain an intermediate 1; adding deionized water into the intermediate 1, and carrying out secondary stirring to form a muddy intermediate 2; the intermediate 2 is subjected to extrusion forming and drying, and a recycled desulfurizer product is obtained; according to the method, valuable elements in the two solid wastes, namely the KR desulfurization slag tailings after magnetic separation and the titanium dioxide industrial byproducts, are subjected to resource utilization through a one-step reaction method, the two solid wastes are converted into high-added-value products, and the method has a relatively large application and popularization space.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid waste resource utilization, and particularly relates to a method for highly valuable utilization of KR desulfurized slag tailings and a desulfurizer. Background Art

[0002] The KR desulfurization technology has been widely used in modern steelmaking production due to its high desulfurization performance and stable operation. In this process, hot metal is poured into a treatment tank with a stirrer made of refractory materials. By rotating the stirrer, the hot metal forms a vortex inside the treatment tank, and then a desulfurizer (usually a calcium-based material) is added to make the hot metal and the desulfurizer fully react to produce sulfides. After the reaction is completed, the desulfurized slag containing sulfides floats on the surface of the hot metal, and the generated slag layer (KR desulfurized slag) is removed by slag skimming.

[0003] At present, the main treatment method for RK desulfurized slag is to separate the iron and slag in the desulfurized slag by means of rod milling and magnetic separation. The separated steel slag and magnetic separation powder are sent to the converter steelmaking and iron ore sintering respectively, and the remaining tailings are usually returned to the sintering machine as a flux. For example, Chinese Patent CN113373275A discloses a method for internal recycling of KR desulfurized slag in a steel plant. The KR desulfurized slag is crushed and then subjected to magnetic separation to obtain slag iron and tailings; then the tailings are subjected to high-temperature oxidation treatment to obtain sulfur-containing flue gas and pre-molten slag; the sulfur-containing flue gas is collected and treated, and the pre-molten slag is used as a slag-making material for the early slag-making of the converter, realizing the internal recycling of KR desulfurized slag in the steel plant. Through the above method, the present invention can effectively separate the slag iron in the KR desulfurized slag from the tailings that are difficult to be recycled, and through the high-temperature oxidation treatment of the tailings, while fully desulfurizing, the iron in the tailings is oxidized into iron oxides to obtain sulfur-free and CaO- and iron oxide-rich pre-molten slag. Furthermore, by utilizing the synergistic effect between CaO and iron oxides, it is used as a slag-making material for the early slag-making of the converter, enabling the iron oxides to promote the rapid dissolution of lime, while realizing the comprehensive utilization of KR desulfurized slag and reducing the slag-making pressure of converter steelmaking.

[0004] Chinese Patent CN111250518A discloses a method for the efficient resource utilization of KR desulfurization slag, belonging to the technical field of comprehensive utilization of metallurgical solid waste resources. First, the desulfurization slag is crushed to a specified particle size, and then the slag iron and tail slag are obtained by magnetic separation. The slag iron is returned to the steelmaking process to replace scrap steel for reuse; the tail slag is further ground and used to replace quicklime in the dry or semi-dry desulfurization process of sintering. The product of dry or semi-dry desulfurization of sintering is desulfurization ash, which participates in sintering ore blending and is used to replace sintered iron-containing raw materials and fluxes according to a certain ratio, which is beneficial to sintering production. During the high-temperature process of sintering, the sulfur element in the desulfurization ash enters the sintering flue gas in the form of SO2. Activated coke is used to adsorb SO2 in the sintering flue gas, and the activated coke adsorbed with SO2 releases SO2 through high-temperature desorption to obtain SO2-rich flue gas. The SO2-rich flue gas is prepared into sulfuric acid with different concentrations through processes such as purification and catalytic oxidation.

[0005] However, although using the KR desulfurization slag tail slag to replace sintering fluxes (sintered quicklime, dolomite) can dispose of the tail slag and reduce the consumption of sintering fluxes, during the sintering process, the sulfides in the KR desulfurization slag tail slag will be converted into SO2 gas under the conditions of high-temperature sintering in the sintering machine, increasing the load of the sintering flue gas desulfurization process and the generation amount of sintering desulfurization ash. Moreover, the added value of replacing sintering fluxes is relatively low. The prices of sintered quicklime and dolomite are usually 60-70 yuan per ton, and the high-value utilization of the KR desulfurization slag tail slag has not been realized. Summary of the Invention

[0006] To solve the above technical problems, the present invention provides a method for the high-value utilization of KR desulfurization slag tail slag, which makes full use of the valuable elements in the tail slag, and through a simple production process, synergistically utilizes it with the by-products of the titanium dioxide industry, and produces a highly efficient desulfurizer with high added value that can be used to remove H2S in natural gas and metallurgical gas through a one-step reaction, and no additional additives are required, which can simultaneously realize the high-value resource utilization of two kinds of industrial solid wastes.

[0007] The present invention also provides a desulfurizer, which is prepared by the method of the present invention and has excellent desulfurization effect.

[0008] The technical solutions adopted by the present invention are as follows:

[0009] A method for the high-value utilization of KR desulfurization slag tail slag, the method comprising the following steps:

[0010] (1) Drying, grinding, and screening the KR desulfurization slag tail slag after magnetic separation, and collecting the undersize;

[0011] (2) Grinding and screening the by-products of the titanium dioxide industry, and collecting the undersize;

[0012] (3) Mix the KR desulfurization slag tail and the titanium dioxide industrial by-product, add deionized water and stir. Continuously introduce air during the stirring process until a muddy mixture is formed. Place the muddy mixture in a storage yard for natural aging to obtain Intermediate 1;

[0013] (4) Add deionized water to Intermediate 1 and perform secondary stirring to form muddy Intermediate 2;

[0014] (5) Extrude and dry Intermediate 2 to obtain a resource-based desulfurizer product.

[0015] In step (1), the drying temperature is 100 - 120 °C, and it is dried until the water content ≤ 0.1%. Usually, the water content of the tailings after magnetic separation is about 10 - 15%. If not dried, problems such as adhesion will occur during ball milling, which is not conducive to subsequent process treatment.

[0016] In steps (1) and (2), the particle size of the undersize material ≤ 200 mesh; the oversize material is returned to the ball mill for recycling with the original material.

[0017] In step (3), the KR desulfurization slag tail and the titanium dioxide industrial by-product are mixed according to Ca / Fe = 1.00 - 2.00, where Ca is the weight percentage of the Ca element contained in the KR desulfurization slag tail, and Fe is the weight percentage of the Fe element contained in the titanium dioxide industrial by-product. At such a ratio, the KR desulfurization slag tail and the titanium dioxide industrial by-product can react fully. The reactions occurring during this process are as follows:

[0018] Mainly utilize the effective component Ca(OH)2 in the magnetic separation tailings of KR desulfurization slag to react with the effective component FeSO4 in the titanium dioxide industrial by-product.

[0019] In step (3), the mass ratio of the total mass of the KR desulfurization slag tail and the titanium dioxide industrial by-product to the mass of deionized water is 0.5 - 1:1. Too much water addition is not conducive to the formation of a muddy mixture, and too little water addition is not conducive to the reaction. During the stirring process, introduce excessive air while stirring to accelerate the reaction.

[0020] In step (3), the stirring time is 0.5 - 3 h; the aging time is 80 - 120 h. The aging process is to allow the reaction products of the KR desulfurization slag tail and the titanium dioxide industrial by-product to be fully oxidized, which helps the formation of active iron oxide.

[0021] In step (4), the mass of deionized water is 5 - 20% of the mass of Intermediate 1, which can form a loose muddy substance.

[0022] In step (5), it is extruded into a strip shape with a diameter range of 3 - 7 mm.

[0023] In step (5), the drying temperature is 60 - 90°C, and the drying time is 20 - 40 h. The drying temperature should not be too high. When the temperature exceeds 100°C, the active components in the produced desulfurizer will turn into Fe2O3 without crystal water, thus losing the desulfurization activity.

[0024] The present invention also provides a desulfurizer prepared by the method of the present invention, and the desulfurizer has excellent desulfurization effect.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The method for high-value utilization of KR desulfurization slag tail slag provided by the present invention realizes the resource utilization of valuable elements in two solid wastes, namely the magnetic-separated KR desulfurization slag tail slag and the by-product of titanium dioxide industry, through a one-step reaction method, realizes the digestion of solid waste, and the process scheme will not release the sulfides that have been fixed in the KR desulfurization slag.

[0027] The present invention can convert two solid wastes into high-value products, and has great application and promotion space. Moreover, both the KR desulfurization tail slag and the by-product of titanium dioxide industry belong to solid wastes, and the sulfiding agent made from them has the advantages of large output and low price.

[0028] The method for high-value utilization of KR desulfurization slag tail slag provided by the present invention is convenient and simple, and the added value of the resource-based product is high. The raw materials used are solid wastes with a price of about 100 - 200 yuan / ton, and the price of the produced H2S desulfurizer for gas is about 2000 - 3000 yuan / ton, having excellent economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is the XRD phase analysis diagram of the tail slag of the KR desulfurization slag after magnetic separation;

[0030] Figure 2 It is the XRD phase analysis diagram of the resource-based desulfurizer product produced in Example 1;

[0031] Figure 3 It is the XRD phase analysis diagram of the resource-based desulfurizer product produced in Example 2;

[0032] Figure 4 It is the technical roadmap of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0033] The present invention will be described in detail below in conjunction with examples.

[0034] In the magnetic-separated KR desulfurization slag tail slag used in the examples, the contents of its main components are shown in Table 1, and its XRD is as Figure 1 shown.

[0035] Table 1 Main components of the tailings after magnetic separation of KR desulfurization slag, wt%

[0036] Name TFe MFe Ca Mg Si Al Ti Mn S Content 5.52 2.32 43.70 0.45 3.65 0.50 0.10 0.19 2.08

[0037] In the titanium dioxide industrial by-products used in the examples, the main components are shown in Table 2.

[0038] Table 2 Main components in the titanium dioxide industrial by-product (ferrous sulfate) of a certain factory, wt%

[0039] Name Fe Ti Mg Mn Al Content 18.89 0.39 0.48 0.12 0.0095

[0040] Example 1

[0041] A method for high-value utilization of KR desulfurization slag tailings includes the following steps:

[0042] (1) Take 100 g of the tailings of KR desulfurization slag after magnetic separation, put it into a hot air oven and dry it at 102 °C for 12 hours until its water content ≤ 0.1%. The dried tailings are put into a ball mill for processing. After processing, the powder is passed through a 200-mesh sieve, and the powder under the sieve is taken for standby.

[0043] (2) Take 100 g of the titanium dioxide industrial by-product and put it into a ball mill for processing. After processing, the powder is passed through a 200-mesh sieve, and the powder under the sieve is taken for standby.

[0044] (3) Take 22.92 g of the KR desulfurization slag tail powder and 27.32 g of the titanium dioxide industrial by-product powder (Ca / Fe: 1.94), place them on a constant temperature stirring table, and add 60 mL of deionized water for stirring. The temperature during stirring is 30 °C, the stirring time is 30 min, and air is continuously introduced during stirring. The stirred mud-like product is aged in the air for 100 h.

[0045] (4) Take the aged dry mud-like material and put it into a beaker. Add 30 mL of deionized water and stir to form a viscous mud-like material. Use a briquetting machine to extrude desulfurization agents with a diameter of 3 mm, and place them in a hot air oven for low-temperature drying. The drying temperature is 70 °C and the drying time is 24 h to obtain a resource-based desulfurization agent product.

[0046] Example 2

[0047] A method for high-value utilization of KR desulfurization slag tailings includes the following steps:

[0048] (1) Take 100 g of the tailings of KR desulfurization slag after magnetic separation, put it into a hot air oven and dry it at 110 °C for 12 hours until its water content ≤ 0.1%. The dried tailings are put into a ball mill for processing. After processing, the powder is passed through a 200-mesh sieve, and the powder under the sieve is taken for standby.

[0049] (2) Take 100 g of titanium dioxide industrial by-products and put them into a ball mill for processing. After processing, the powder is sieved through a 200-mesh sieve, and the powder under the sieve is reserved for use.

[0050] (3) Take 11.47 g of KR desulfurization slag tail powder and 22.11 g of titanium dioxide industrial by-product powder and mix them (Ca / Fe: 1.20). Place the mixture on a constant-temperature stirring table, add 50 mL of deionized water and stir. The temperature during stirring is 30 °C, the stirring time is 30 min, and air is continuously introduced during stirring. Place the stirred muddy product in the air for aging for 80 h.

[0051] (4) Take the aged dry muddy product and put it into a beaker. Add 30 mL of deionized water and stir to form a viscous muddy product. Use a briquetting machine to extrude desulfurizer strips with a diameter of 3 mm, and place them in a hot air oven for low-temperature drying. The drying temperature is 70 °C, and the drying time is 24 h to obtain a resource-based desulfurizer product.

[0052] Comparative Example 1

[0053] (1) Take 100 g of the KR desulfurization slag tailings after magnetic separation and put them into a hot air oven for drying at 102 °C for 12 hours until its water content ≤ 0.1%. The dried tailings are put into a ball mill for processing. After processing, the powder is sieved through a 200-mesh sieve, and the powder under the sieve is reserved for use.

[0054] (2) Take 100 g of titanium dioxide industrial by-products and put them into a ball mill for processing. After processing, the powder is sieved through a 200-mesh sieve, and the powder under the sieve is reserved for use.

[0055] (3) Take 22.92 g of KR desulfurization slag tail powder and 70.71 g of titanium dioxide industrial by-product powder and mix them (Ca / Fe: 0.75). Place the mixture on a constant-temperature stirring table, add 60 mL of deionized water and stir. The temperature during stirring is 30 °C, the stirring time is 30 min, and air is continuously introduced during stirring. Place the stirred muddy product in the air for aging for 100 h.

[0056] (4) Take the aged dry muddy product and put it into a beaker. Add 30 mL of deionized water and stir to form a viscous muddy product. Use a briquetting machine to extrude desulfurizer strips with a diameter of 3 mm, and place them in a hot air oven for low-temperature drying. The drying temperature is 70 °C, and the drying time is 24 h to obtain a resource-based desulfurizer product.

[0057] Perform performance evaluation on the resource-based desulfurizer products prepared in each example and comparative example, and use a fixed-bed reaction device to test their sulfide adsorption capacity. Silver nitrate solution is used as the breakthrough display signal at the end. When black precipitates appear in the solution, it is considered that the desulfurizer has been penetrated. The test conditions are: the raw gas concentration is H2S: 30000 ppm, and the rest is N2; the reaction space velocity is 2400 h -1; The test results are shown in Table 3.

[0058] Table 2 Evaluation results of desulfurization ability

[0059]

[0060]

[0061] The evaluation results show that the resource-based desulfurizer products prepared in the examples have good desulfurization performance.

[0062] Figure 2 , 3 They are the XRD phase analysis diagrams of the resource-based desulfurizer products produced in Examples 1 and 2 respectively. It can be seen the diffraction peaks of active iron oxide (FeOOH, Fe2O3) and CaSO4. CaSO4 can be directly used as a good additive, and there is no need to add other additives additionally during the production of the desulfurizer.

[0063] The above detailed description of a method for high-value utilization of KR desulfurized slag tailings and a desulfurizer with reference to the examples is illustrative rather than restrictive. Several examples can be listed according to the defined scope. Therefore, changes and modifications within the general concept of the present invention should fall within the protection scope of the present invention.

Claims

1. A method for highly valuable utilization of KR desulfurization slag tailings, characterized in that, The method includes the following steps: (1) Dry, grind, and screen the tailings of KR desulfurized slag after magnetic separation, and collect the undersize material; (2) Grind and screen the by-products of the titanium dioxide industry, and collect the undersize material; (3) Mix the tailings of KR desulfurized slag and the by-products of the titanium dioxide industry, add deionized water and stir, continuously introduce air during the stirring process until a mud-like mixture is formed, and place the mud-like mixture in a stacking yard for natural aging to obtain Intermediate 1; (4) Add deionized water to Intermediate 1 and perform secondary stirring to form a mud-like Intermediate 2; (5) Extrude and dry Intermediate 2 to obtain a resource-based desulfurizer product.

2. The method for highly valuable utilization of KR desulfurized slag tailings according to claim 1, wherein In step (1), the drying temperature is 100-120°C, and it is dried until the water content ≤ 0.1%.

3. The method for high-value utilization of KR desulfurized slag tailings according to claim 1, wherein, In steps (1) and (2), the particle size of the undersize material ≤ 200 mesh.

4. The method for highly value-added utilization of KR desulfurized slag tailings according to claim 1, characterized in that, In step (3), the tailings of KR desulfurized slag and the by-products of the titanium dioxide industry are mixed according to Ca / Fe = 1.00-2.00, where Ca is the weight percentage of the Ca element contained in the tailings of KR desulfurized slag, and Fe is the weight percentage of the Fe element contained in the by-products of the titanium dioxide industry.

5. The method for highly valuable utilization of KR desulfurized slag tailings according to claim 1, characterized in that, In step (3), the mass ratio of the total mass of the tailings of KR desulfurized slag and the by-products of the titanium dioxide industry to the mass of deionized water is 0.5-1:

1.

6. The method for high-value utilization of KR desulfurized slag tailings according to claim 1, characterized in that In step (3), the stirring time is 0.5-3 h; the aging time is 80-120 h.

7. The method for high-value utilization of KR desulfurized slag tailings according to claim 1, characterized in that, In step (4), the mass of deionized water is 5-20% of the mass of Intermediate 1.

8. The method for high-value utilization of KR desulfurized slag tailings according to claim 1, characterized in that, In step (5), the extrusion molding is in a strip shape, and the diameter range is 3-7 mm.

9. The method for highly value-added utilization of KR desulfurized slag tailings according to claim 1, characterized in that, In step (5), the drying temperature is 60-90°C, and the drying time is 20-40 h.

10. A desulfurizer, characterized in that, The desulfurizer is prepared by the method described in any one of claims 1-9.

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