An improver and process for preparing steel shot by reconstructing molten steel slag

Abstract

The present invention belongs to the technical field of metal abrasives, and particularly relates to a modifier and a process for preparing steel casting shots by reconstructing molten steel slag. The mass percentages of the main chemical components of the modifier are as follows: Al2O3 10 - 50%, CaO 10 - 50%, Cr 5 - 10%, Mn 0.2 - 5.5%, and Mg 0.1 - 7%. The present invention provides a modifier and a process for preparing steel casting shots by reconstructing molten steel slag, which can solve the problems of resource recovery and efficient utilization of molten steel slag for reconstructing reduced iron, improve the utilization rate of the waste heat of molten slag, reduce the production cost of steel casting shots, and realize the collaborative utilization among various industrial solid wastes.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal abrasives, and particularly relates to an improver and a process for preparing steel casting shots by reconstructing molten steel slag. Background Art

[0002] Prior art:

[0003] Steel slag is the molten slag discharged during the steelmaking process, and its quantity is 15-20% of the steel output. During the steelmaking production process, since the molten steel and the molten slag are mutually immiscible, the molten steel and the molten slag can be well separated, and the separated molten slag is the steel slag. With the development of the iron and steel industry, the quantity of steel slag is also increasing. The steel slag produced in China each year reaches nearly 100 million tons, and the solid waste resource utilization rate of steel slag is about 50-60%. The main utilization methods are backfilling or road construction. Since the chemical composition of steel slag is similar to that of Portland cement clinker, it is commonly used as a cement admixture and a concrete admixture. The free CaO and MgO commonly present in steel slag result in poor stability of steel slag as a cementitious material and cannot be directly incorporated into cement or concrete as an admixture. Its utilization rate in the building materials industry is only about 10%. In addition, steel slag also contains about 30% Tfe, and the recovery rate of general magnetic separation process is only about 33%. The rest remains in the residue, causing waste of iron resources, and the iron in steel slag will also affect the cementitious activity of steel slag. At present, steel slag is in a low-value utilization mode, and the utilization of steel slag does not achieve the purpose of efficient resource recovery and utilization.

[0004] Considering that the steel slag is in a molten state during the slag discharging process, with a temperature as high as 1500-1600°C, a regulating material containing silicon-aluminum and reducing properties is added to the molten slag to reduce free CaO and stabilize the quality of steel slag and recover iron resources. The reduced iron generated during the reconstruction process and the residue are two mutually immiscible phases. After the separation of slag and iron, the separated residue can be directly incorporated into cement or concrete as an admixture and be fully utilized. Due to the large amount of slag, the molten steel after separation is 1 / 3-1 / 4 of the residue amount. If it is directly transported back to the converter as a steelmaking raw material, the transportation frequency is high, increasing the production difficulty and having a greater impact on the production of the original process. If the molten iron is directly cooled, a large amount of heat will be wasted. The efficient utilization of reconstructed reduced iron is an urgent problem to be solved.

[0005] With the development of China's industry, millions of tons of steel casting shots are consumed every year for the cleaning and strengthening of the surfaces of steel materials and castings in the equipment manufacturing industry. Among them, 30% of the steel casting shots are imported, and the steel casting shots produced in China far cannot meet the market demand. At present, many enterprises use scrap steel to produce steel casting shots, but due to the shortage and high price of scrap steel resources in China, the cost of steel casting shots produced by many enterprises is relatively high. Therefore, the demand of relevant production enterprises for low-cost steel casting shots is becoming increasingly strong.

[0006] China generates a large amount of industrial solid waste every year, including fly ash, coal gangue, asbestos tailings, iron tailings, manganese slag, waste soil, vanadium slag, magnesium slag, wulfenite, barite, aluminum ash, magnesite, etc. If not disposed of in time, these solid wastes will occupy a large amount of land and cause environmental pollution, affecting human health. The above industrial solid wastes are formulated into regulators and modifiers in a certain proportion to modify steel slag and improve the reconstructed reduced iron, so as to realize the collaborative utilization among industrial solid wastes.

[0007] Difficulty and significance of solving the above technical problems:

[0008] Therefore, based on these problems, it is of great practical value to provide a modifier and process for preparing steel shot by reconstructing molten steel slag, which can solve the resource recovery and efficient utilization of reconstructed reduced iron from molten steel slag, improve the waste heat utilization rate of molten slag, reduce the production cost of steel shot, and realize the collaborative utilization among various industrial solid wastes. Summary of the Invention

[0009] The purpose of this application is to provide a modifier and process for preparing steel shot by reconstructing molten steel slag, which can solve the resource recovery and efficient utilization of reconstructed reduced iron from molten steel slag, improve the waste heat utilization rate of molten slag, reduce the production cost of steel shot, and realize the collaborative utilization among various industrial solid wastes, so as to solve the technical problems in the prior art.

[0010] The technical solution adopted in the embodiments of this application to solve the technical problems existing in the known technology is:

[0011] A modifier for preparing steel shot by reconstructing molten steel slag, the mass percentages of the main chemical components of the modifier are: Al2O3 10 - 50%, CaO 10 - 50%, Cr 5 - 10%, Mn 0.2 - 5.5%, Mg 0.1 - 7%.

[0012] The embodiments of this application can also adopt the following technical solutions:

[0013] In the above-mentioned modifier for preparing steel shot by reconstructing molten steel slag, further, the modifier includes one or several of aluminum ash with a mass percentage of 31 - 65%, magnesium slag with a mass percentage of 2 - 11%, manganese slag with a mass percentage of 3 - 7%, chromium slag with a mass percentage of 6 - 13%, quicklime with a mass percentage of 10 - 47%, and magnesite with a mass percentage of 0 - 2%.

[0014] In the above-mentioned modifier for preparing steel shot by reconstructing molten steel slag, further, the water content of the modifier ≤ 1.1% and the particle size ≤ 2mm.

[0015] A process for preparing steel shot by reconstructing molten steel slag, the process for preparing steel shot by reconstructing molten steel slag includes the following steps:

[0016] Step 1: Adding a regulator: Transfer the molten steel slag from the converter of the steel mill to the regulating furnace, add a regulator according to 10 - 30% of the mass of the molten steel slag in the regulating furnace to reduce the iron oxides in the steel slag, and adjust other element components in the molten iron to make a primary improvement. Keep the temperature in the regulating furnace at ≥1550 °C and maintain it for more than 40 minutes until the reduction reaction of the iron in the molten steel slag is completed;

[0017] Step 2: Separating iron from slag: Discharge the molten iron from the bottom of the regulating furnace, and granulate the remaining slag by cooling. The molten iron is continuously transferred to the improvement furnace;

[0018] Step 3: Adding the said improver: Add an improver according to 1 - 10% of the mass of the molten iron in the improvement furnace, keep the temperature at ≥1600 °C, and keep the improvement time of the molten iron for more than 30 minutes;

[0019] Step 4: Granulation: Granulate the improved molten iron to prepare steel casting shots.

[0020] The regulator reacts with the molten steel slag in the electric furnace to temper the molten steel slag. The iron oxides in the steel slag are reduced to elemental iron. Since the density of iron is greater than that of the remaining slag, iron and the remaining slag are stratified, and the molten iron is discharged to separate the molten iron from the remaining slag. After decarbonization, dephosphorization and desulfurization treatment of the separated molten iron, granulation and screening treatment are carried out. The remaining slag generated by the present invention has no risk of soundness and can be used as a raw material to be incorporated into cement to realize the resource utilization of waste.

[0021] The present invention uses solid waste as the raw material of the regulator and improver to dispose of steel slag, and uses the improved molten iron as the raw material to produce steel casting shots, realizing "making the best use of everything". It can also solve the problems of waste of iron oxide resources in the hot stamping treatment process of steel slag, large safety risks in the application of the remaining slag as building materials, and limited use.

[0022] The present invention solves the problem of resource utilization of reconstructing and reducing iron from molten steel slag. Utilizing the heat contained in the molten steel slag, by adding a regulator, the iron oxides contained in the molten steel slag are reduced to molten iron and remaining slag, and the molten iron and the remaining slag are separated. After adding an improver to the molten iron for decarbonization and deharm treatment of the iron, steel casting shots are obtained after granulation, drying and screening.

[0023] The hardness of the steel casting shots prepared by reconstructing molten steel slag using solid waste can reach HRC40 - 52, meeting the GBT18838.4 - 2008 standard, and can be used for shot peening cleaning, strengthening, forming, etc.

[0024] In the above process of preparing steel casting shots by reconstructing molten steel slag, further, after the said Step 4, there are the following steps:

[0025] Step 5: Screening: Screen according to the particle size of the steel casting shots after granulation. The large - particle steel casting shots need to be crushed into steel sand for use;

[0026] Step 6: Heat treatment: Quench and temper the steel shot. Heat the steel shot at 750 - 1000 °C, hold for 30 - 60 min, and then cool it in water for quenching; heat the quenched steel shot at 150 - 650 °C and hold for 30 - 60 min for tempering.

[0027] In the above process of preparing steel shot by reconstructing molten steel slag, further, the mass percentages of the main chemical components of the regulator in Step 1 are as follows: SiO2 5 - 50%, CaO 10 - 30%, Al2O3 7 - 60%, C 6 - 15%, Ba 0 - 2%, Mg 0.1 - 2%, V 0 - 0.5%.

[0028] In the above process of preparing steel shot by reconstructing molten steel slag, further, the moisture content of the tempering agent ≤ 1.3% and the particle size ≤ 2 mm.

[0029] In the above process of preparing steel shot by reconstructing molten steel slag, further, the tempering agent includes one or more of fly ash with a mass percentage of 3 - 27%, coal gangue with a mass percentage of 4 - 10%, aluminum ash with a mass percentage of 7 - 52%, asbestos tailings with a mass percentage of 4 - 18%, iron tailings with a mass percentage of 18 - 25%, quicklime with a mass percentage of 8 - 10%, waste soil with a mass percentage of 1 - 5%, vanadium slag with a mass percentage of 0 - 2%, magnesium slag with a mass percentage of 0 - 2%, wulfenite with a mass percentage of 0 - 1%, barite with a mass percentage of 0 - 1%, and coke pellets with a mass percentage of 4 - 15%.

[0030] In the above process of preparing steel shot by reconstructing molten steel slag, further, the granulation in Step 4 adopts one or more of the drum method, air jet injection method, air spraying method, water jet impact method, and centrifugal atomization method.

[0031] In the above process of preparing steel shot by reconstructing molten steel slag, further, the steps before Step 1 include the following: Pretreatment of drying, crushing, and screening of the regulator and the modifier:

[0032] Modifier: One or more of aluminum ash, magnesium slag, manganese slag, chromium slag, quicklime, and magnesite are used as raw materials for the modifier, dried and crushed to a moisture content ≤ 1.1% and a particle size ≤ 2 mm, and then mixed evenly by a mixer. The drying temperature is 300 - 500 °C;

[0033] Regulator: One or more of fly ash, coal gangue, asbestos tailings, iron tailings, manganese slag, waste soil, vanadium slag, magnesium slag, wulfenite, barite, and coke pellets are used as raw materials for the regulator, dried and crushed to a moisture content ≤ 1.3% and a particle size ≤ 2 mm, and then mixed evenly by a mixer. The drying temperature is 200 - 400 °C.

[0034] The raw material components of the regulator and the modifier have all been dried and crushed. For the raw materials of the regulator that do not meet the conditions of moisture ≤ 1.3% and particle size ≤ 2 mm, they need to be returned to the raw material bin for secondary drying and crushing, and the drying temperature is 200 - 400 °C. The raw materials of the modifier are dried and crushed to moisture ≤ 1.1% and particle size ≤ 2 mm. The raw materials that do not meet the conditions need to be returned to the raw material bin for secondary drying and crushing, and the drying temperature is 300 - 500 °C.

[0035] One or more technical solutions provided in the embodiments of the present application have at least the following beneficial effects:

[0036] 1. The present invention uses industrial solid waste as the raw material for steel slag reconstruction reduction and reduced iron modification, which can dispose of a large amount of industrial solid waste, reduce waste emissions, lower the costs of steel slag reconstruction reduction and reduced iron modification, and the products produced have high economic value and broad market prospects.

[0037] 2. In the present invention, samples are taken from the raw materials of the selected regulator and modifier before use, and the particle size and moisture of the samples are measured. For the raw materials of the regulator that do not meet the conditions of moisture ≤ 1.3% and particle size ≤ 2 mm, and the raw materials of the modifier that do not meet the conditions of moisture ≤ 1.1% and particle size ≤ 2 mm, they need to enter the mill for drying and crushing. If they still do not meet the conditions after the first drying and crushing, they need to be subjected to secondary drying and crushing. If the particle size meets the requirements but the moisture does not meet the requirements, the raw materials can be added to the fluidized bed, and the heat source provided by the hot blast stove is used to heat and dry the raw materials. If the moisture meets the requirements but the particle size does not meet the requirements, they are returned to the mill for crushing.

[0038] 3. Due to the element adjustment of the molten reduced iron water modification treatment and then through the heat treatment technical solution in the present invention, the produced steel shot has moderate hardness, good wear resistance, good toughness, is not easy to break and has fewer cracks under the condition of multiple repeated impact tests, and the production process is simple, which is suitable for large-scale promotion.

[0039] 4. The elements such as Mn, Si, Cr, V, etc. and the raw materials in the steel shot produced by the present invention all come from industrial solid waste, which greatly reduces the cost of the element ore powder added in the traditional process, reduces the production cost, and meets the strong demand of relevant enterprises for cheap raw materials.

[0040] 5. The Mn element added to the steel shot of the present invention can dissolve into the ferrite to cause solid solution strengthening, increasing the strength and hardness of the steel shot. Mn and Si can play the role of composite deoxidation of molten steel, and Mn can also form manganese sulfide with sulfur elements, reducing the harmful effects of sulfur elements on the steel shot. Vanadium and iron can form a continuous solid solution, strongly narrowing the austenite phase region.

[0041] 6. Compared with traditional slag landfill, hot stewing and other treatment processes, the present invention makes full use of the heat in the slag and adds a regulator to reconstruct and reduce the slag. The remaining slag after separation of iron slag is used as a raw material for building materials, and the molten iron is used as a raw material for cast steel shots. This reduces the smelting link in the traditional cast steel shot production process, reduces energy consumption, reduces carbon emissions, reduces the production cost of cast steel shots, and makes high added value use of the slag. DETAILED DESCRIPTION

[0042] The regulator for steel slag reconstruction and reduction is mainly composed of one or more of fly ash, coal gangue, asbestos tailings, iron tailings, manganese slag, spoil, vanadium slag, magnesium slag, witherite, barite, coke particles, etc. The percentage of the main chemical components of the regulator is SiO2 5-50%, CaO 10-30%, Al2O3 7-60%, C 6-15%, Ba 0-2%, Mg 0.1-2%, V0-0.5%. The molten iron improver includes one or more of aluminum ash, magnesium slag, manganese slag, chromium slag, quicklime, and magnesite. The percentage of the main chemical components of the improver is Al2O3 10-50%, CaO 10-50%, Cr 5-10%, Mn 0.2-5.5%, Mg 0.1-7%.

[0043] The raw materials of the regulator and the improver are dried and crushed. The raw materials of the regulator that do not meet the conditions of moisture ≤1.3% and particle size ≤2mm need to be returned to the raw material warehouse for secondary drying and crushing, and the drying temperature is 200-400℃. The raw materials of the improver are dried and crushed to moisture ≤1.1% and particle size ≤2mm. The raw materials that do not meet the conditions need to be returned to the raw material warehouse for secondary drying and crushing, and the drying temperature is 300-500℃.

[0044] The converter molten slag is first poured into the transfer tank, and then transferred to the tempering furnace by the 1# transfer tank. The temperature is raised to maintain the fluidity of the slag. The bottom blowing of the tempering furnace is opened while the modifier is added, so that the modifier is evenly dispersed in the molten slag. After sufficient reaction, the molten iron is discharged from the bottom of the regulating furnace to the 2# transfer tank and transferred to the improvement furnace. The temperature is raised to maintain the fluidity of the molten iron. The modifier is added and oxygen is continuously blown into the furnace so that the modifier is evenly dispersed in the molten iron. After the improved molten iron removes the upper slag, it is transferred to the bottom leakage limiting flow pouring cup of the centrifugal pool through the 3# transfer tank. Through the action of centrifugal force, the molten iron is thrown out from the centrifugal brick into the water and forms cast steel shots after cooling.

[0045] Add a regulator at 10 - 30% of the mass of molten steel slag. To fully maintain the fluidity of the molten steel slag, adjust the furnace temperature ≥ 1550°C. To fully reduce the iron in the steel slag, maintain the steel slag reconstruction reaction time above 40 min. Add a modifier at 1 - 10% of the mass of hot metal in the improved furnace. To fully maintain the fluidity of the hot metal, adjust the furnace temperature ≥ 1600°C. To ensure that elements such as Mg, Cr, and Mn in the modifier fully enter the hot metal, maintain the hot metal improvement time above 30 min.

[0046] The diameter of the steel shot produced by the centrifugal atomization method mainly concentrates at 12 - 18 mesh (1.0 - 1.7 mm). To improve the toughness and strength of the steel shot, perform quenching and tempering treatments on the steel shot. Heat the steel shot at 750 - 1000°C, keep it warm for 30 - 60 min, and then cool it in water for quenching treatment. Heat the quenched steel shot at 150 - 650°C and keep it warm for 30 - 60 min for tempering treatment.

[0047] The regulating furnace and the improving furnace are general heating devices such as industrial electric furnaces.

[0048] This embodiment includes the following steps:

[0049] (1) Preparation of the regulator. Raw materials such as fly ash, coal gangue, aluminum ash, asbestos tailings, iron tailings, manganese slag, waste soil, vanadium slag, magnesium slag, wulfenite, barite, and coke particles are classified according to moisture content and particle fineness. Raw materials that do not meet the requirements (moisture ≤ 1.3%, particle size ≤ 2 mm) need to be sent to a drying crusher for drying and crushing treatment until they meet the requirements. Raw materials that meet the requirements do not need to go through the drying and crushing treatment and are directly sent to a mixer to prepare the regulator. The chemical components of the regulator finished product meet SiO2 5 - 50%, CaO 10 - 30%, Al2O3

[0050] 7 - 60%, C 6 - 15%, Ba 0 - 2%, Mg 0.1 - 2%, V 0 - 0.5% by mass ratio.

[0051] The drying temperature during the drying and crushing process is 200 - 400°C, and the drying temperature can be adjusted according to the moisture of the dried raw materials.

[0052] Preparation of the modifier. Raw materials such as aluminum ash, magnesium slag, manganese slag, chromium slag, quicklime, and magnesite are classified according to moisture content and particle fineness. Raw materials that do not meet the requirements (moisture ≤ 1.1%, particle size ≤ 2 mm) are sent to a drying crusher for drying and crushing treatment until they meet the requirements. Raw materials that meet the requirements do not need to go through the drying and crushing treatment and are directly sent to a mixer to prepare the modifier. The chemical components of the modifier finished product meet Al2O3 10 - 50%, CaO 10 - 50%, Cr 5 - 10%, Mn 0.2 - 5.5%, Mg 0.1 - 7% by mass ratio.

[0053] (2) Adding a regulator. The molten steel slag is first heated in a conditioning furnace to ≥1550 °C, and a regulator is added at 10-30% of the mass of the molten steel slag. A reconstruction reduction reaction occurs between the molten steel slag and the regulator, and the molten iron produced by reduction is located at the bottom of the furnace due to its density being greater than that of the remaining slag. The holding time for this process is more than 40 minutes.

[0054] (3) Adding an improver. The slag is transferred from the bottom of the conditioning furnace to an improvement furnace and heated to ≥1600 °C. An improver is added at 1-10% of the mass of the molten iron in the improvement furnace, and oxygen is blown in from the bottom of the improvement furnace to perform decarburization, desulfurization, dephosphorization, etc. on the molten iron. The impurities in the improver and the molten iron are two immiscible phases, and due to the density difference, the impurities float on the upper layer of the molten steel.

[0055] (4) Granulation. The improved molten steel is poured into a flow-limiting pouring cup, and then the molten steel flows through the flow-limiting pouring cup into a high-speed rotating centrifugal brick. Under the action of centrifugal force, the molten steel is thrown out from the pores of the centrifugal brick and falls into water, forming cast steel shot after cooling. The rotation speed of the centrifugal brick is 1100-1300 r / min, and the outflow rate of the molten steel is 100 Kg / min.

[0056] (5) Screening. Screening is carried out according to the particle size of the cast steel shot after granulation. The large-particle cast steel shot needs to be crushed into steel sand for use.

[0057] (6) Heat treatment. Quenching and tempering treatments are carried out on the screened cast steel shot. The cast steel shot is heated at 750-1000 °C, held for 30-60 minutes, and then cooled in water for quenching treatment; the quenched cast steel shot is heated at 150-650 °C and held for 30-60 minutes for tempering treatment.

[0058] (7) Packaging. The cast steel shot is subjected to packaging treatment.

[0059] In order to better understand the above technical solution, the above technical solution will be described in detail below in combination with the embodiments of the specification and specific implementation manners.

[0060] Example 1

[0061] The mass ratio of each raw material component of the regulator provided in this example is 16% fly ash, 10% coal gangue, 8% aluminum ash, 10% asbestos tailings, 25% iron tailings, 10% quicklime, 5% waste soil, 2% magnesium slag, and 15% coke particles. The formula and composition of the regulator are shown in Table 1.

[0062] Table 1 Regulator formula and chemical composition / %

[0063]

[0064] The percentage of each raw material component of the modifier provided in this embodiment is 58% aluminum ash, 7% magnesium slag, 7% manganese slag, 12% chromium slag, 14% quicklime, and 2% magnesite. The formula and composition of the modifier are shown in Table 2.

[0065] Table 2 Formula and Chemical Composition of Modifier / %

[0066]

[0067]

[0068] The temperature of the molten steel slag tapped from the converter is 1600 °C. The molten steel slag and the regulator are poured into the regulating furnace synchronously, and the temperature of the regulating furnace is maintained at ≥1550 °C for 40 min. A reconstruction reduction reaction occurs in the regulating furnace. The density of the molten iron produced by reduction is greater than that of the remaining slag. The molten iron and the remaining slag are two immiscible phases, and the molten iron is discharged from the lower end of the reformed furnace. The main chemical composition detection results of the molten steel slag and the molten iron are shown in Tables 3 and 4.

[0069] Table 3 Main Chemical Composition of Molten Steel Slag Discharged from Converter / %

[0070] <![CDATA[SiO2]]> <![CDATA[Al2O3]]> CaO MgO TFe Converter steel slag 10.25 5.62 42.13 6.55 29.36

[0071] Table 4 Main Chemical Composition of Molten Iron / %

[0072] Fe C Si Mn Mg V S P Hot metal 93.68 4.65 0.24 0.20 0.12 0 0.022 0.032

[0073] The temperature of the molten steel tapped from the conditioning furnace is 1650 °C. The molten steel slag and the modifier are poured into the modification furnace synchronously, and the temperature of the regulating furnace is maintained at ≥1600 °C for 30 min. The oxygen blown in from the bottom of the modification furnace will take away the carbon in the molten iron to form CO and CO2; the added Mn element can improve the deoxidation effect of Si and Al, and can combine with sulfur to form manganese sulfide to eliminate the harmful effect of sulfur; the added Al element can improve the oxidation resistance, corrosion resistance of the steel shot product and discharge gas impurities, and inhibit the generation of pores and looseness in the steel shot. The molten steel and the remaining slag formed after modification are two immiscible phases, and the remaining slag floats on the upper end of the molten steel. The main chemical composition detection result of the molten steel is shown in Table 5.

[0074] Table 5 Main Chemical Composition of Molten Steel / %

[0075] Fe C Si Mn Mg V Cr S P Liquid steel 97.12 0.22 0.29 0.28 0.16 0 0.25 0.016 0.028

[0076] The modified molten steel is poured into a flow-limiting pouring cup, and then the molten steel flows through the flow-limiting pouring cup into a centrifugal brick rotating at a high speed. Under the action of centrifugal force, the molten steel is thrown out from the pores of the centrifugal brick and falls into water, and forms steel shots after cooling. The rotation speed of the centrifugal brick is 1100 r / min, and the molten steel outflow rate is 100 Kg / min. The particle size distribution of the steel shots is mainly shown in Table 6.

[0077] Table 6 Cast steel shot particle size distribution / %

[0078] 0 - 10 mesh 10 - 20 mesh 20 - 30 mesh Over 30 mesh Particle size 3.5 53.6 30.2 12.7

[0079] The sieved cast steel shot was quenched and tempered. The cast steel shot was heated at 750 °C, held for 30 min and then cooled in water for quenching; the quenched cast steel shot was heated at 150 °C and held for 30 min for tempering. The Owen cycle life of the Owen life tester was used with 100% substitution method. An experimental sieve with a pore size of 0.425 mm was used to screen the worn cast steel shot, and the measurement results are shown in Table 7.

[0080] Table 7 Measurement results of Owen life of cast steel shot by 100% substitution method

[0081]

[0082] The hardness of the cast steel shot was measured as HRC48, meeting the requirements of the GBT18838.4-2008 standard for the hardness of steel shot being HRC40 - 52, and it can be safely used in cleaning operations such as shot blasting, strengthening, and forming.

[0083] Example 2

[0084] The mass ratio of each raw material component of the regulator provided in this example is 3% fly ash, 4% coal gangue, 52% aluminum ash, 4% asbestos tailings, 18% iron tailings, 8% quicklime, 1% waste soil, 2% vanadium slag, 2% magnesium slag, 1% wulfenite, 1% barite, 4% coke particles. The regulator formula and composition are shown in Table 8.

[0085] Table 8 Regulator formula and chemical composition / %

[0086]

[0087] The percentage of each raw material component of the improver provided in this example is 31% aluminum ash, 11% magnesium slag, 3% manganese slag, 6% chromium slag, 47% quicklime, 2% magnesite. The improver formula and composition are shown in Table 9.

[0088] Table 9 Improver formula and chemical composition / %

[0089]

[0090] The temperature of the molten steel slag tapped from the converter is 1600 °C. The molten steel slag and the regulator are poured into the regulation furnace synchronously, maintaining the temperature of the regulation furnace ≥1550 °C and holding for 40 min. A reconstruction reduction reaction occurs in the regulation furnace. The density of the molten iron is greater than that of the remaining slag, and the molten iron and the remaining slag are two immiscible phases. The molten iron is discharged from the lower end of the reforming furnace. The main chemical composition detection results of the molten steel slag and the molten iron are shown in Table 10 and Table 11.

[0091] Table 10 Main Chemical Compositions of Molten Steel Slag Discharged from Converter / %

[0092] <![CDATA[SiO2]]> <![CDATA[Al2O3]]> CaO MgO TFe Converter steel slag 10.28 5.42 42.23 6.45 29.46

[0093] Table 11 Main Chemical Compositions of Hot Metal / %

[0094] Fe C Si Mn Mg V S P Hot metal 93.68 3.65 0.18 0.26 0.29 0.16 0.028 0.039

[0095] The temperature of the molten steel tapped from the quenching and tempering furnace is 1650 °C. The molten steel slag and the modifier are poured into the modification furnace synchronously, and the temperature of the adjustment furnace is maintained at ≥1600 °C for 30 min. The test results of the main chemical compositions of the molten steel are shown in Table 12.

[0096] Table 12 Main Chemical Compositions of Molten Steel / %

[0097] Fe C Si Mn Mg V Cr S P Liquid steel 97.16 0.16 0.22 0.72 0.38 0.15 0.55 0.019 0.034

[0098] The modified molten steel is poured into a flow-limiting pouring cup, and then the molten steel flows into a high-speed rotating centrifugal brick through the flow-limiting pouring cup. Under the action of centrifugal force, the molten steel is thrown out from the pores of the centrifugal brick and falls into the water, and steel shot is formed after cooling. The rotation speed of the centrifugal brick is 1200 r / min, and the outflow rate of the molten steel is 100 Kg / min. The particle size distribution of the steel shot is mainly shown in Table 13.

[0099] Table 13 Particle Size Distribution of Steel Shot / %

[0100] 0 - 10 mesh 10 - 20 mesh 20 - 30 mesh Over 30 mesh Particle size 4.6 56.6 29.1 9.7

[0101] The sieved steel shot is subjected to quenching and tempering treatments. The steel shot is heated at 850 °C, held for 45 min and then cooled in water for quenching treatment; the quenched steel shot is heated at 350 °C and held for 45 min for tempering treatment. The Owen cycle life of 100% substitution method is used with an Owen life testing machine, and a test sieve with a pore diameter of 0.425 mm is used to screen the worn steel shot. The test results are shown in Table 14.

[0102] Table 14 Test Results of Owen Life of Steel Shot by 100% Substitution Method

[0103]

[0104]

[0105] The hardness of the steel shot is measured as HRC50, which meets the requirements of the steel shot hardness of HRC40 - 52 in the GBT18838.4 - 2008 standard and can be safely used in shot blasting cleaning, strengthening, forming and other cleaning operations.

[0106] Example 3

[0107] The mass ratio of each raw material component of the regulator provided in this embodiment is 27% fly ash, 7% coal gangue, 23% aluminum ash, 4% asbestos tailings, 18% iron tailings, 9% quicklime, 2% waste soil, 1% vanadium slag, 2% magnesium slag, and 7% coke particles. The formula and composition of the regulator are shown in Table 15.

[0108] Table 15 Formula and Chemical Composition of the Regulator / %

[0109]

[0110] The percentage of each raw material component of the improver provided in this embodiment is 65% aluminum ash, 2% magnesium slag, 7% manganese slag, 13% chromium slag, 10% quicklime, and 2% magnesite. The formula and composition of the improver are shown in Table 16.

[0111] Table 16 Formula and Chemical Composition of the Improver / %

[0112]

[0113]

[0114] The temperature of the molten steel slag taken out from the converter is 1600 °C. The molten steel slag and the regulator are poured into the regulating furnace synchronously, and the temperature of the regulating furnace is maintained at ≥1550 °C for 40 minutes. A restructuring reduction reaction occurs in the regulating furnace. The density of the molten iron is greater than that of the remaining slag. The molten iron and the remaining slag are two immiscible phases, and the molten iron is discharged from the lower end of the reforming furnace. The main chemical composition detection results of the molten steel slag and the molten iron are shown in Tables 17 and 18.

[0115] Table 17 Main Chemical Composition of the Molten Steel Slag Discharged from the Converter / %

[0116] <![CDATA[SiO2]]> <![CDATA[Al2O3]]> CaO MgO TFe Converter steel slag 10.66 5.12 43.23 5.45 30.46

[0117] Table 18 Main Chemical Composition of the Molten Iron / %

[0118] Fe C Si Mn Mg V S P Hot metal 94.68 2.89 0.26 0.79 0.19 0.26 0.038 0.041

[0119] The temperature of the molten steel taken out from the conditioning furnace is 1650 °C. The molten steel slag and the improver are poured into the improving furnace synchronously, and the temperature of the regulating furnace is maintained at ≥1600 °C for 30 minutes. The main chemical composition detection results of the molten steel are shown in Table 19.

[0120] Table 19 Main Chemical Composition of the Molten Steel / %

[0121] Fe C Si Mn Mg V Cr S P Liquid steel 97.16 0.28 0.19 0.98 0.18 0.20 0.85 0.026 0.030

[0122] The improved molten steel is poured into a flow-limiting pouring cup, and then the molten steel flows through the flow-limiting pouring cup into a centrifugal brick that rotates at a high speed. Under the action of centrifugal force, the molten steel is thrown out from the pores of the centrifugal brick and falls into water, and after cooling, steel shot is formed. The rotation speed of the centrifugal brick is 1300 r / min, and the outflow rate of the molten steel is 100 Kg / min. The particle size distribution of the steel shot is mainly shown in Table 20.

[0123] Table 20 Particle size distribution of steel shot / %

[0124] 0 - 10 mesh 10 - 20 mesh 20 - 30 mesh Over 30 mesh Particle size 6.5 58.6 26.1 8.8

[0125] The sieved steel shot is subjected to quenching and tempering treatments. The steel shot is heated at 1000 °C, held for 60 min, and then cooled in water for quenching treatment; the quenched steel shot is heated at 650 °C and held for 60 min for tempering treatment. The Owen cycle life of 100% replacement method is used with an Owen life tester, and an experimental sieve with a pore diameter of 0.425 mm is used to screen the worn steel shot, and the measurement results are shown in Table 21.

[0126] Table 21 Measurement results of Owen life of steel shot by 100% replacement method

[0127]

[0128]

[0129] The hardness of the steel shot is measured as HRC54, which meets the requirements of the steel shot hardness of HRC40 - 52 in the GBT18838.4 - 2008 standard, and it can be safely used in cleaning operations such as shot peening cleaning, strengthening, and forming.

[0130] Through Examples 1 to 3, the raw materials used for the regulator and modifier in the preparation of steel shot by reconstructing molten steel slag in the present invention are basically composed of industrial solid wastes. The raw materials are pretreated according to the moisture and particle size of the raw materials, and after meeting the requirements, the raw materials are mixed evenly and then made into a regulator and a modifier. The molten steel slag is reconstructed and reduced to molten iron by the regulator, and the molten iron is improved by the modifier and then centrifugally atomized to produce steel shot. The steel shot is subjected to heat treatment such as quenching and tempering, and then the Owen life and hardness are tested. The Owen life can reach more than 4000 times, and the hardness meets the requirements of HRC40 - 52 in the GBT18838.4 - 2008 standard. The measurement results of the composition of the improved molten iron used in the production of steel shot meet the chemical composition of the ISO11124 - 4 standard.

[0131] The process and method for preparing steel shot by reconstructing solid waste molten steel slag according to the present invention use regulators and modifiers both composed of industrial solid wastes such as fly ash, coal gangue, and aluminum ash. The composition of the modified molten iron meets the chemical composition of the ISO11124-4 standard, and the hardness of the produced steel shot meets the requirements of the GBT18838.4-2008 standard. The present invention makes full use of the waste heat of the steel slag and the iron contained in the steel slag to produce steel shot, while reducing energy consumption, greatly reducing the production cost of steel shot, realizing a high-value utilization mode of steel slag, and at the same time achieving the coordinated disposal of solid wastes in multiple industries.

[0132] In summary, the present invention provides a modifier and process for preparing steel shot by reconstructing molten steel slag, which can solve the problems of resource recovery and efficient utilization of molten steel slag for reconstructing reduced iron, improve the utilization rate of waste heat of molten slag, reduce the production cost of steel shot, and realize the coordinated utilization among various industrial solid wastes.

[0133] The above embodiments have described the present invention in detail, but the described content is only the preferred embodiments of the present invention and cannot be considered as limiting the scope of implementation of the present invention. All equivalent changes and improvements made according to the scope of the present invention application shall still fall within the scope covered by the patent of the present invention.

Claims

1. A process for preparing steel shot by reconstructing molten steel slag, characterized in that: The process for preparing steel shot by reconstructing molten steel slag includes the following steps: Step 1: Adding a regulator: Transfer the molten steel slag from the converter of the steel plant to the regulating furnace. Add a regulator according to 10 - 30% of the mass of the molten steel slag in the regulating furnace to reduce the iron oxides in the steel slag and adjust the other element components in the molten iron for primary improvement. Keep the temperature in the regulating furnace at ≥1550°C and for more than 40 minutes until the reduction reaction of the iron in the molten steel slag is completed. The mass percentages of the main chemical components of the regulator in Step 1 are: SiO2 5 - 50%, CaO 10 - 30%, Al2O3 7 - 60%, C 6 - 15%, Ba 0 - 2%, Mg 0.1 - 2%, V 0 - 0.5%; Step 2: Separating iron from slag: Discharge the molten iron from the bottom of the regulating furnace, and granulate the remaining slag by cooling. The molten iron is continuously transferred to the improvement furnace; Step 3: Adding an improver: Add an improver according to 1 - 10% of the mass of the molten iron in the improvement furnace. Keep the temperature at ≥1600°C and blow oxygen from the bottom of the improvement furnace to carry out decarburization, desulfurization, and dephosphorization treatment on the molten iron, and keep the improvement time of the molten iron for more than 30 minutes. The mass percentages of the main chemical components of the improver are: Al2O3 10 - 50%, CaO 10 - 50%, Cr 5 - 10%, Mn 0.2 - 5.5%, Mg 0.1 - 7%; Step 4: Granulation: Granulate the improved molten steel to prepare steel shot.

2. The process for preparing steel shot by reconstructing molten steel slag according to claim 1, characterized in that: The improver includes 31 - 65% aluminum ash, 2 - 11% magnesium slag, 3 - 7% manganese slag, 6 - 13% chromium slag, 10 - 47% quicklime, and 0 - 2% magnesite by mass percentage.

3. The process for preparing steel shot by reconstructing molten steel slag according to claim 1, characterized in that: The moisture content of the improver is ≤1.1% and the particle size is ≤2mm.

4. The process for preparing steel shot by reconstructing molten steel slag according to claim 1, characterized in that: After Step 4, there are the following steps: Step 5: Screening: Screen according to the particle size of the steel shot after granulation. The large - sized steel shot needs to be crushed into steel sand for use; Step 6: Heat treatment: Quench and temper the steel shot. Heat the steel shot at 750 - 1000°C, keep it warm for 30 - 60 minutes, and then cool it in water for quenching treatment; Heat the quenched steel shot at 150 - 650°C, keep it warm for 30 - 60 minutes for tempering treatment.

5. The process for preparing steel shot by reconstructing molten steel slag according to claim 1, characterized in that: The moisture content of the regulator is ≤1.3% and the particle size is ≤2mm.

6. The process for preparing steel shot by reconstructing molten steel slag according to claim 1, characterized in that: The regulator includes 3 - 27% fly ash, 4 - 10% coal gangue, 7 - 52% aluminum ash, 4 - 18% asbestos tailings, 18 - 25% iron tailings, 8 - 10% quicklime, 1 - 5% waste soil, 0 - 2% vanadium slag, 0 - 2% magnesium slag, 0 - 1% wulfenite, 0 - 1% barite, and 4 - 15% coke particles by mass percentage.

7. The process for preparing steel shot by reconstructing molten steel slag according to claim 1, characterized in that: The granulation in Step 4 adopts one or several of the roller method, air spraying method, water jet impact method, and centrifugal atomization method.

8. The process for preparing steel shot by reconstructing molten steel slag according to claim 1, characterized in that: Before Step 1, there are the following steps: Pretreat the regulator and the improver by drying, crushing, and screening: Improvement agent: The aluminum ash, magnesium slag, manganese slag, chromium slag, quicklime, and magnesite are used as raw materials for the improvement agent, dried and crushed to a moisture content of ≤1.1% and a particle size of ≤2 mm, and then mixed evenly by a mixer. The drying temperature is 300~500 °C; Regulator: The fly ash, coal gangue, asbestos tailings, iron tailings, manganese slag, waste soil, vanadium slag, magnesium slag, wulfenite, barite, and coke particles are used as raw materials for the regulator, dried and crushed to a moisture content of ≤1.3% and a particle size of ≤2 mm, and then mixed evenly by a mixer. The drying temperature is 200~400 °C.

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