CN111590033A - Safe and environment-friendly preparation method of silicon-strontium inoculant - Google Patents
Safe and environment-friendly preparation method of silicon-strontium inoculant Download PDFInfo
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- CN111590033A CN111590033A CN202010493863.2A CN202010493863A CN111590033A CN 111590033 A CN111590033 A CN 111590033A CN 202010493863 A CN202010493863 A CN 202010493863A CN 111590033 A CN111590033 A CN 111590033A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D1/00—Treatment of fused masses in the ladle or the supply runners before casting
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C1/00—Refining of pig-iron; Cast iron
- C21C1/10—Making spheroidal graphite cast-iron
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0006—Adding metallic additives
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Abstract
The invention discloses a safe and environment-friendly preparation method of a silicon-strontium inoculant, which comprises the following steps: step 1) raw material preparation: preparing high-purity strontium metal and low-aluminum ferrosilicon; making the metal strontium into a plurality of metal strontium blocks with the weight not more than 1.5 kg; step 2) putting the low-aluminum ferrosilicon into a medium-frequency electric furnace for melting to form a low-aluminum ferrosilicon melt; the tapping temperature of the low-aluminum silicon iron melt is not lower than 1450 ℃; step 3) pouring the low-aluminum silicon iron melt into a ladle; step 4) adding the metal strontium blocks in the step 1 into a ladle through a strontium pressing device, and removing the strontium pressing device after the metal strontium blocks are subjected to melting reaction; step 5), stirring the melt in the ladle; step 6) slowly casting the melt in the step 5 into an inoculant mold ingot as soon as possible; step 7), standing and cooling; and 8) demolding. The method for preparing the silicon-strontium inoculant by adopting the strontium pressing method is firstly proposed, and compared with a complete melting method in which furnace burden is completely added into an intermediate frequency furnace, the method is relatively safe and has high metal yield.
Description
Technical Field
The invention belongs to the field of casting materials, relates to a production process of an inoculant, and particularly relates to a safe and environment-friendly preparation method of a silicon-strontium inoculant.
Background
The comprehensive performance of the nodular cast iron is close to that of steel, and the nodular cast iron is widely applied to casting mechanical parts with complex stress and higher requirements on strength, toughness and wear resistance based on the excellent performance of the nodular cast iron. Nodular cast iron is a cast iron material which is second to gray cast iron and has wide application.
There are various ways to improve the mechanical property of the nodular cast iron material, wherein the inoculation is a simple, economic and effective method. The inoculation treatment has the effect of improving the mechanical property and the processing property of the cast iron from the following aspects:
1) the solidification condition of the nodular cast iron eutectic crystal is changed, the tendency of crystal supercooling and the tendency of white cast caused by spheroidizing elements are eliminated, and the cast without free cementite in the cast state is obtained.
2) Promoting graphitization, increasing graphite core, refining spherical graphite, improving the relative stability of the growth of the spherical graphite and improving the roundness of graphite spheres.
3) The eutectic clusters are refined, so that the segregation degree among the eutectic clusters is reduced, the uniformity of the structure is improved, the mechanical property is improved, and the elongation and the impact toughness of the casting are improved.
The inoculant plays an important role in the quality and cost of the iron castings, and proper inoculant inoculation treatment is selected according to conditions.
The common inoculant used in enterprises is 75 ferrosilicon inoculant, and the addition amount of the inoculant is generally 0.6-1.2%. However, the effect of ferrosilicon as an inoculant is quite limited, so people add various trace elements into the ferrosilicon to develop various compound inoculants. If adding in ferrosilicon: barium, calcium, strontium, zirconium, strontium, antimony, rare earth and other elements, and can raise inoculation effect, reduce chilling tendency, raise tensile strength and improve the microstructure and mechanical performance of nodular cast iron. And the addition amount of the compound inoculant is greatly reduced.
The addition of the silicon-strontium inoculant into the nodular cast iron has the effects of a ferrosilicon inoculant and also has a plurality of unique characteristics:
1. has strong capability of eliminating and reducing the chilling tendency, has long duration and is a long-acting inoculant for resisting spheroidization recession.
2. The eutectic group number of the cast iron is not increased remarkably, the shape and distribution condition of graphite in the thin-wall casting are improved, the difference of tissues at different thicknesses is smaller, and the supercooled tissues are only seen on the surface layer of the casting, so that the shrinkage porosity tendency can be reduced, and the compactness and the water pressure resistance of the casting are improved.
3. The silicon carbide has extremely strong graphitization capability, and the addition amount of the silicon carbide is only 50-30% of that of 75 ferrosilicon.
4. The melting temperature range is 1210-. The strontium is added into the nodular cast iron melt in an alloy state, has low melting point compared with ferrosilicon, low calcium and aluminum content, easy dissolution, less slag formation and lower inoculation temperature. The temperature range allowed for inoculation is 1360-.
The most of the silicon-strontium inoculants prepared industrially adopt a carbothermic method and a smelting method. The silicon-strontium inoculant is prepared by a medium-frequency induction furnace and a smelting method, and most of the silicon-strontium inoculant is prepared by adding all furnace materials into a hearth together for smelting. The melting temperature of 75 low-aluminum ferrosilicon is 1290-1340 ℃, and the melting temperature of strontium metal is 769 ℃. Because the melting temperature difference is more, and the melting temperature difference are simultaneously put into a furnace for smelting, so that the burning loss of the metal strontium is serious. One of the main consumption modes of low melting point metals is melting loss, volatilization,
the melting point of the metal strontium is 769 ℃, the melting point of 75 ferrosilicon (containing 72-80 percent of silicon) is 1290-1340 ℃, and the difference between the melting temperatures of the metal strontium and the 75 ferrosilicon reaches more than 500 ℃. The silicon-strontium inoculant is prepared by a medium-frequency induction furnace by adopting a melting and matching method, and the common method is to add all raw materials into a hearth for melting at one time, so that the burning loss of the metal strontium is large. Not only wastes the valuable and scarce metal of strontium, but also pollutes the environment.
Most of the traditional methods for preparing the silicon-strontium inoculant adopt a vacuum electric furnace melting and matching method or a medium-frequency electric furnace complete melting and matching method. The single-furnace yield of the silicon-strontium inoculant prepared by the vacuum electric furnace melting and matching method is more than dozens of kilograms, and the scale benefit is difficult to form. The intermediate frequency electric furnace complete melting method for preparing the silicon-strontium inoculant has the advantages that as the furnace burden is completely added into the furnace for smelting, the metal burning loss rate, particularly the burning loss of low-melting-point metal is higher, the metal strontium is easy to splash in the smelting process, and the hidden trouble of production safety accidents exists.
Therefore, a proper smelting mode and an alloying treatment temperature are developed, and the low-melting-point metal loss is reduced.
Disclosure of Invention
The invention aims to solve the technical problem of providing a safe and environment-friendly preparation method of a silicon-strontium inoculant aiming at the defects of the prior art, and particularly provides a method for preparing the silicon-strontium inoculant by adopting an external ladle strontium pressing method. For the first time, the method for preparing the silicon-strontium inoculant by adopting an external ladle strontium pressing method is proposed; the strontium-silicon inoculant prepared by the strontium pressing method obviously improves the operation safety, can effectively solve the problem of large burning loss of the metal strontium, can efficiently produce the strontium-silicon inoculant, has high metal yield and reduces the pollution to the environment.
The technical scheme is as follows: a preparation method of a safe and environment-friendly silicon-strontium inoculant comprises the following steps:
step 1) raw material preparation: preparing high-purity strontium metal and low-aluminum ferrosilicon; making the metal strontium into a plurality of metal strontium blocks with the weight not more than 1.5 kg;
step 2) putting the low-aluminum ferrosilicon into a medium-frequency electric furnace for melting to form a low-aluminum ferrosilicon melt; the tapping temperature of the low-aluminum silicon iron melt is not lower than 1450 ℃;
step 3) pouring the low-aluminum silicon iron melt obtained in the step 2 into a ladle;
step 4) adding the metal strontium blocks in the step 1 into a ladle through a strontium pressing device, and removing the strontium pressing device after the metal strontium blocks are subjected to melting reaction;
step 5), stirring the melt in the ladle;
step 6) slowly casting the melt in the step 5 into an inoculant mold ingot as soon as possible;
step 7), standing and cooling to form a silicon-strontium inoculant;
and 8) demolding.
The method of the invention firstly proposes that the strontium-silicon inoculant is prepared by adopting a strontium pressing method, which is safer than a complete melting method that the furnace burden is completely added into a medium frequency furnace, the metal yield is high, and particularly the yield of low-melting-point metal strontium is improved.
In the method, the low-aluminum silicon iron melt is formed by melting in the medium-frequency electric furnace, so that the low-melting-point metal is melted and prepared outside the furnace, the metal burning loss is reduced, and the metal yield is improved. Compared with the complete melting and matching method, the metal yield is improved by 2-3 percent.
In the method of the present invention, the number and volume of the pressed-in strontium metal blocks are limited in consideration of the specific heat capacities of the ferrosilicon melt and the pressed-in strontium metal blocks. The ladle and the strontium press also consume heat. The strontium content in the strontium-silicon prepared by the strontium pressing method is not more than 2 percent, and the weight of each metal strontium block is not more than 1.5 kg.
The technical scheme of the invention is further defined as follows:
the low-aluminum silicon iron TFeSi75-A comprises the chemical components of TFeSi75-A in percentage by mass, 74-80% of Si, less than or equal to 1.0% of Ca and less than or equal to 0.5% of Al; the Sr content of the metal strontium blocks is more than or equal to 99 percent. The raw materials are prepared according to the target components of the inoculant; the silicon-strontium inoculant has higher requirements on the content of Ca and Al, and if the content of Ca and Al in the silicon-strontium inoculant is high, the graphitization capability of Sr can be counteracted. Therefore, the contents of Ca and Al in the silicon-strontium inoculant are generally controlled as follows: ca is less than or equal to 0.1 percent and Al is less than or equal to 0.5 percent. In order to ensure that the final components of the silicon-strontium inoculant meet the requirements, the raw materials are preferably low-aluminum-silicon iron TFeSi75-A and high-purity strontium Sr more than or equal to 99%, the low-aluminum-silicon iron TFeSi75-A and TFeSi75-A comprise the following chemical components in percentage by mass, Si is 74-80, Ca is less than or equal to 1.0, and Al is less than or equal to 0.5.
According to the requirement that the strontium content in the industrial common strontium-silicon inoculant is usually less than or equal to 2 percent, the metal strontium block added into the ladle each time does not exceed 2 percent. According to the method, when the strontium-silicon inoculant is prepared by adopting a strontium pressing method, the more cold strontium metal needs to be pressed into the melt to be molten when the content of the strontium metal is higher. The low-Al ferrosilicon which participates in the heat exchange needs to be heated to a high temperature so as to melt the strontium metal in the nodulizing ladle. Colloquially, hot ferrosilicon low in aluminum does not melt as much cold strontium metal. Therefore, the content of the metal strontium in the patent cannot be high, and is not more than 2%. The strontium content of the common industrial silicon-strontium inoculant is usually less than or equal to 2 percent.
The strontium pressing device comprises a strontium pressing protective cover, a hoisting core rod and a rigging shackle, wherein the strontium pressing protective cover covers an opening of the ladle, a metal strontium block is suspended on the lower end face of the hoisting core rod, the hoisting core rod penetrates through the strontium pressing protective cover in a sliding mode to press the metal strontium block into the ladle, and the rigging shackle is arranged at the top of the hoisting core rod and used for being connected with external hoisting equipment.
According to the method, a hoisting core rod of the strontium pressing device can penetrate through a strontium pressing protective cover to move up and down, and when the strontium pressing protective cover covers a ladle, the hoisting core rod is continuously lowered to a molten inoculant to be pressed into a strontium block; thereby remarkably improving the operation safety and the metal yield and reducing the pollution to the environment.
The strontium-pressing protective cover is cast and molded by adopting heat-resistant cast iron, and the periphery of the strontium-pressing protective cover is provided with a skirt edge; a conical through hole for the hoisting core rod to penetrate through is formed in the center of the strontium pressing protective cover; the center of the strontium pressing protective cover is provided with a circular reinforcing boss, and the conical through hole is positioned at the axis of the circular reinforcing boss. In the method, the strontium pressing protective cover is made of cast iron, and has the advantages that firstly, the strontium pressing protective cover is high-temperature resistant and not easy to melt, and secondly, the weight is increased, so that the strontium pressing device cannot float or tilt in a melt. The skirt design of the periphery of the strontium-pressing protective cover ensures that the strontium-pressing protective cover completely covers the ladle. The crossing hole is matched with the inclination of a triangular reinforcing rib on the hoisting core rod, so that the strontium pressing protective cover can be automatically aligned without deflection. The design of the circular reinforcing boss improves the strength of the center of the strontium pressing protective cover.
The hoisting core bar comprises a core bar main body, a plurality of limiting baffle plates, a strontium pressing disc and a plurality of triangular reinforcing ribs which play a role in guiding the hoisting core bar and a strontium pressing protective cover, wherein the strontium pressing disc is arranged at the lower end of the core bar main body, and a plurality of round holes for penetrating iron wires for binding the metal strontium blocks are formed in the strontium pressing disc; a plurality of triangular reinforcing ribs are uniformly welded at the joint of the strontium pressing disc and the core bar main body; a plurality of limiting baffles are uniformly distributed on the outer wall of the upper part of the core rod main body; the top of the core rod main body is welded with a hoisting lug. The triangular reinforcing rib in the hoisting core rod is used for matching with the through hole with inclination on the strontium pressing protective cover to play a role in alignment and guide. A limit baffle is welded for preventing the strontium pressing disc from colliding with the bottom of the ladle. And a hoisting lug ring is welded at the top for hoisting.
The external hoisting equipment is a bridge crane, and a hook of the bridge crane is connected with a rigging shackle through a chain. The chain adopts a mining high-strength round-link chain, one end of the round-link chain is connected with the rigging shackle, and the other end of the round-link chain is connected with the lifting hook of the bridge crane.
Step 4, adding the metal strontium block in the step 1 into a foundry ladle through a strontium pressing device, and comprising the following steps:
step 4.1) assembling the strontium pressing device;
step 4.2) binding and suspending the metal strontium block which needs to be pressed into the ladle below the circular strontium pressing disc by using an iron wire;
step 4.3), external hoisting equipment hoists the strontium pressing device to the upper part of the ladle, and the strontium pressing device is lowered; the strontium pressing protective cover firstly covers the opening of the ladle, and a hoisting core rod of the strontium pressing device continuously descends to press the metal strontium block into the low-aluminum silicon iron melt in the ladle;
and 4.4) after the melting reaction of the metal strontium blocks is finished, external hoisting equipment hoists a hoisting core rod of the strontium pressing device and removes the strontium pressing device.
In the method, because the metal strontium blocks are pressed into the inoculant melt to reduce the burning loss of strontium, the yield of the strontium is improved by 2-3 percent and is higher than that of a complete melting method in which furnace burden is completely added into an intermediate frequency furnace. In the whole strontium pressing process, the ladle filled with the inoculant melt is covered firstly, and then the metallic strontium is pressed, so that the pollution to the environment is reduced, the operation condition is improved, and the safety of the production process is improved.
In the step 6, when the thickness of the casting mold ingot is more than 100mm, the components of the inoculant are easy to segregate. Casting of ingots having a thickness greater than 100mm should be avoided. The thickness of the inoculant mold is less than 100mm, and one-time casting is finished. In the slow cooling process of the liquid ferrosilicon, the silicon-rich part with low density floats upwards, and the iron silicide with high density sinks, so that the components of the ferrosilicon are segregated. In order to reduce segregation of ferrosilicon ingots, it is necessary to lower the ferrosilicon casting temperature, control the ingot thickness, or perform layered casting and increase the ingot cooling rate. In order to prevent the component segregation of the strontium-silicon inoculant after casting, the thickness of the cast ingot is controlled to be less than 100mm, and the casting is finished at one time.
And 6, hoisting the ladle by the travelling crane, and manually rotating a rotating hand wheel on the ladle for casting.
Compared with the prior art, the invention has the beneficial effects that:
1. the method firstly proposes that the strontium-silicon inoculant is prepared by adopting a strontium pressing method, is relatively safe compared with a complete melting method in which furnace burden is completely added into an intermediate frequency furnace, has high metal yield, and particularly improves the yield of low-melting-point metal strontium.
2. The production practice proves that the single-furnace yield can reach 500-600kg by adopting the 3-ton intermediate frequency electric furnace to prepare the silicon-strontium inoculant, and the method has obvious scale benefit; large-scale production, high production efficiency and production cost saving.
3. The method has the advantages that the low-melting-point metal is melted and prepared outside the furnace, the metal burning loss is reduced, and the metal yield is improved. Compared with the complete melting and matching method, the metal yield is improved by 2-3 percent.
Drawings
Fig. 1 is a front view of the present invention.
Fig. 2 is a cross-sectional view of a strontium-pressed protective cover.
Fig. 3 is a schematic view of the lifting core rod.
Figure 4 is a schematic view of a rigging shackle.
Fig. 5 is a state diagram of the strontium pressing apparatus of example 1 before the strontium block is pressed in.
Fig. 6 is a state diagram of the strontium pressing apparatus of example 1 after the strontium block is pressed in.
Wherein: 1-strontium pressing protective cover, 11-through hole, 2-hoisting core bar, 21-core bar main body, 22-strontium pressing disc, 23-limit baffle, 24-triangular reinforcing rib, 25-round hole, 26-hoisting lug ring, 3-rigging shackle, 4-strontium metal block, 5-ladle, 6-external hoisting equipment, 7-chain and 8-low-aluminum ferrosilicon melt.
Detailed Description
The technical solution of the present invention is described in detail below, but the scope of the present invention is not limited to the embodiments.
In order to make the disclosure of the present invention more comprehensible, the following description is further made in conjunction with fig. 1 to 6 and the detailed description.
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Example 1
The preparation method of the safe and environment-friendly silicon-strontium inoculant provided by the embodiment comprises the following steps of:
step 1) raw material preparation: preparing high-purity strontium metal and low-aluminum ferrosilicon; making the metal strontium into a plurality of metal strontium blocks with the weight not more than 1.5 kg;
step 2) putting the low-aluminum ferrosilicon into a medium-frequency electric furnace for melting to form a low-aluminum ferrosilicon melt; the tapping temperature of the low-aluminum silicon iron melt is not lower than 1450 ℃;
step 3) pouring the low-aluminum silicon iron melt obtained in the step 2 into a ladle;
step 4) adding the metal strontium blocks in the step 1 into a ladle through a strontium pressing device, and removing the strontium pressing device after the metal strontium blocks are subjected to melting reaction;
step 5), stirring the melt in the ladle;
step 6) slowly casting the melt in the step 5 into an inoculant mold ingot as soon as possible;
step 7), standing and cooling to form a silicon-strontium inoculant;
and 8) demolding.
In the embodiment, raw materials are prepared according to the target components of the inoculant; the silicon-strontium inoculant has higher requirements on the content of Ca and Al, and if the content of Ca and Al in the silicon-strontium inoculant is high, the graphitization capability of Sr can be counteracted. Therefore, the contents of Ca and Al in the silicon-strontium inoculant are generally controlled as follows: ca is less than or equal to 0.1 percent and Al is less than or equal to 0.5 percent. In order to ensure that the final components of the silicon-strontium inoculant meet the requirements, the raw materials are preferably low-aluminum-silicon iron TFeSi75-A and high-purity strontium Sr more than or equal to 99%, the low-aluminum-silicon iron TFeSi75-A and TFeSi75-A comprise the following chemical components in percentage by mass, Si is 74-80, Ca is less than or equal to 1.0, and Al is less than or equal to 0.5.
In the embodiment, the low-aluminum silicon iron melt is melted in a medium-frequency electric furnace to form a low-aluminum silicon iron melt; therefore, the method for preparing the low-melting-point metal by melting outside the furnace reduces the metal burning loss and improves the metal yield by 2-3 percent compared with the complete melting preparation method.
In this example, the number and volume of the pressed-in strontium metal blocks are limited in consideration of the specific heat capacities of the ferrosilicon melt and the pressed-in strontium metal blocks. The ladle and the strontium press also consume heat. The strontium content in the strontium-silicon prepared by the strontium pressing method is not more than 2 percent, and the weight of each metal strontium block is not more than 1.5 kg.
In this example, the amount of strontium in the ladle per charge of metal strontium mass is not more than 2% according to the requirement of strontium content in the industrial common strontium-silicon inoculant being usually not more than 2%. When the strontium pressing method is adopted to prepare the strontium-silicon inoculant, the higher the content of the strontium metal is, the more the cold strontium metal needs to be pressed into the melt for melting. The low-Al ferrosilicon which participates in the heat exchange needs to be heated to a high temperature so as to melt the strontium metal in the nodulizing ladle. Colloquially, hot ferrosilicon low in aluminum does not melt as much cold strontium metal. Therefore, the content of the metal strontium in the patent cannot be high, and is not more than 2%. The strontium content of the common industrial silicon-strontium inoculant is usually less than or equal to 2 percent.
As shown in fig. 1, the strontium pressing device comprises a strontium pressing protective cover 1, a hoisting core bar 2 and a rigging shackle 3, wherein the strontium pressing protective cover 1 covers an opening of a ladle 5, a strontium metal block 4 is suspended on the lower end surface of the hoisting core bar 2, the hoisting core bar 2 penetrates through the strontium pressing protective cover 1 in a sliding manner to press the strontium metal block 4 into the ladle 5, and the rigging shackle 3 is arranged at the top of the hoisting core bar 2 and used for connecting an external hoisting device 6.
As shown in figure 2, the strontium-pressing protective cover 1 is made of heat-resistant cast iron by casting, and the strontium-pressing protective cover is made of cast iron, so that the strontium-pressing protective cover has the advantages of high temperature resistance and difficulty in melting, and the weight is increased to ensure that the strontium-pressing device cannot float or tilt in a melt. The medium-pressure strontium protective cover 1 is preferably made of nodular cast iron and vermicular cast iron, and the heat resistance of the nodular cast iron and the vermicular cast iron is sequentially higher than that of common cast iron.
As shown in fig. 2, a tapered through hole 11 for the hoisting core bar 2 to penetrate through is formed in the center of the strontium pressing protective cover 1, and the through hole is matched with the inclination of a triangular reinforcing rib on the hoisting core bar, so that the strontium pressing protective cover can be automatically aligned without being skewed. The center of the strontium pressing protective cover 1 is provided with a circular reinforcing boss, and the strength of the center of the strontium pressing protective cover is improved by the design of the circular reinforcing boss. The conical through hole 11 is positioned at the axle center of the circular reinforcing boss. The periphery of the strontium-pressing protective cover 1 is provided with a skirt edge, so that the strontium-pressing protective cover completely covers the ladle.
As shown in fig. 3, the hoisting core bar 2 comprises a core bar main body 21, a plurality of limit baffles 23, a strontium pressing disc 22 and a plurality of triangular reinforcing ribs 24 which play a role of guiding the hoisting core bar 2 and the strontium pressing protective cover 1, the strontium pressing disc 22 is arranged at the lower end of the core bar main body 21, and a plurality of round holes 25 for penetrating iron wires binding the strontium metal blocks are arranged on the strontium pressing disc 22; a plurality of triangular reinforcing ribs 24 are uniformly welded at the joint of the strontium pressing disc 22 and the core bar main body 21; the triangular reinforcing ribs are used for matching with the inclined through holes on the strontium pressing protective cover to play a role in alignment and guide. A plurality of limiting baffles 23 are uniformly welded on the outer wall of the upper part of the core rod main body 21; and the limiting baffle is used for preventing the strontium pressing disc from colliding with the bottom of the ladle. And a hoisting lug 26 is welded at the top of the core rod main body 21 and used for hoisting.
The core rod main body 21 is made of a cast iron pipe with a thick wall, and is made of a steel pipe with a thick wall and is resistant to burning loss. The strontium ram 22 is welded to the lower end of the core rod body 21. The strontium pressing disk 22 is circular.
As shown in fig. 4, the rigging shackle 3 is a "U" shaped shackle, and the U-shaped rigging shackle 3 is inserted into the lifting lug 26 and locked with a bolt.
As shown in fig. 5 and 6, the external hoisting device 6 is a bridge crane, the hook of which is connected to the rigging shackle 3 by means of a chain 7. The chain 7 adopts a mining high-strength round-link chain, one end of the round-link chain is connected with the rigging shackle 3, and the other end of the round-link chain is connected with a lifting hook of the bridge crane.
The strontium pressing method for preparing the strontium-silicon inoculant in the method in the embodiment is to add the strontium metal block in the step 1 into a ladle through a strontium pressing device in the step 4, and comprises the following steps:
step 4.1) assembling the strontium pressing device;
step 4.2) binding and suspending the metal strontium block 4 which needs to be pressed into the ladle 5 below the circular strontium pressing disc 22 by using an iron wire;
step 4.3), the external hoisting equipment 6 hoists the strontium pressing device to the upper part of the ladle 5, and then the strontium pressing device is lowered; the strontium pressing protective cover 1 firstly covers the opening of the ladle 5, and the hoisting core rod 2 of the strontium pressing device continuously descends to press the metal strontium block 4 into the low-aluminum silicon-iron melt 8 in the ladle 5;
and 4.4) after the melting reaction of the metal strontium block 5 is finished, hoisting the hoisting core rod of the strontium pressing device by external hoisting equipment 6, and removing the strontium pressing device.
In the method, because the metal strontium blocks are pressed into the inoculant melt to reduce the burning loss of strontium, the yield of the strontium is improved by 2-3 percent and is higher than that of a complete melting method in which furnace burden is completely added into an intermediate frequency furnace. In the whole strontium pressing process, the ladle filled with the inoculant melt is covered firstly, and then the metallic strontium is pressed, so that the pollution to the environment is reduced, the operation condition is improved, and the safety of the production process is improved.
In step 6 of this example, when the thickness of the cast ingot is greater than 100mm, the inoculant component is likely to segregate. Casting of ingots having a thickness greater than 100mm should be avoided. The thickness of the inoculant mold is less than 100mm, and one-time casting is finished. In the slow cooling process of the liquid ferrosilicon, the silicon-rich part with low density floats upwards, and the iron silicide with high density sinks, so that the components of the ferrosilicon are segregated. In order to reduce segregation of ferrosilicon ingots, it is necessary to lower the ferrosilicon casting temperature, control the ingot thickness, or perform layered casting and increase the ingot cooling rate. In order to prevent the component segregation of the strontium-silicon inoculant after casting, the thickness of the cast ingot is controlled to be less than 100mm, and the casting is finished at one time.
And 6, hoisting the ladle by the travelling crane, and manually rotating a rotating hand wheel on the ladle for casting.
The working process of the embodiment:
binding a metal strontium block 4 below a circular strontium pressing disc 22 by using an iron wire, operating a bridge crane to lift a strontium pressing device above a ladle 5, putting a low-aluminum silicon-iron melt 8 into the ladle 5, and lowering the strontium pressing device; the strontium pressing protective cover 1 firstly covers the opening of the ladle 5, and the hoisting core rod 2 of the strontium pressing device continuously descends to press the metal strontium block 4 into the ladle 5. After the metal strontium block 4 is melted and reacted, the strontium pressing device is lifted, and the inoculant mold ingot is slowly poured after stirring.
Because the burning loss of the strontium can be reduced by pressing the metal strontium blocks into the inoculant melt, the yield of the strontium is improved by 2-3 percent and is higher than that of a complete melting and matching method in which all furnace charge is added into an intermediate frequency furnace. In the whole strontium pressing process, the ladle filled with the inoculant melt is covered firstly, and then the metallic strontium is pressed, so that the pollution to the environment is reduced, and the operation condition is improved. The safety of the production process is improved. As shown in fig. 5 and 6.
The strontium-silicon inoculant prepared by the strontium pressing method has the following advantages:
1. because the metal strontium is not added into the furnace for melting, the metal strontium is only melted in the foundry ladle, the melting temperature is reduced, and the strontium yield can be improved.
2. The strontium pressing method can effectively reduce metal splashing, even if the metal splashing is accidentally blocked by the protective cover of the strontium pressing device, and the operation safety is improved.
3. After standing for deslagging, pressing in metal strontium, which can improve the purity of silicon strontium.
4. After standing for deslagging, the temperature of the ferrosilicon melt is properly reduced, which is beneficial to reducing the burning loss of the metal strontium.
5. In the process of pressing strontium, the strontium pressing protective cover firstly covers the ladle filled with the inoculant melt and then presses the metal strontium, so that the pollution to the environment is reduced, and the operation condition is improved.
6. The specific weight of the strontium is lighter than that of 75 ferrosilicon, and the strontium can be deeply added into the inoculant melt by adopting a pressing-in method, so that the strontium is melted and reacted at the bottom of the ladle, and the burning loss of the strontium is reduced.
The above embodiments are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modifications made on the basis of the technical scheme according to the technical idea of the present invention fall within the protection scope of the present invention.
Claims (10)
1. A preparation method of a safe and environment-friendly silicon-strontium inoculant is characterized by comprising the following steps: the method comprises the following steps:
step 1) raw material preparation: preparing high-purity strontium metal and low-aluminum ferrosilicon; making the metal strontium into a plurality of metal strontium blocks with the weight not more than 1.5 kg;
step 2) putting the low-aluminum ferrosilicon into a medium-frequency electric furnace for melting to form a low-aluminum ferrosilicon melt; the tapping temperature of the low-aluminum silicon iron melt is not lower than 1450 ℃;
step 3) pouring the low-aluminum silicon iron melt obtained in the step 2 into a ladle;
step 4) adding the metal strontium blocks in the step 1 into a ladle through a strontium pressing device, and removing the strontium pressing device after the metal strontium blocks are subjected to melting reaction;
step 5), stirring the melt in the ladle;
step 6) slowly casting the melt in the step 5 into an inoculant mold ingot as soon as possible;
step 7), standing and cooling to form a silicon-strontium inoculant;
and 8) demolding.
2. The preparation method of the safe and environment-friendly silicon-strontium inoculant as claimed in claim 1, wherein the preparation method comprises the following steps: the low-aluminum silicon iron TFeSi75-A comprises the chemical components of TFeSi75-A in percentage by mass, 74-80% of Si, less than or equal to 1.0% of Ca and less than or equal to 0.5% of Al; the Sr content of the metal strontium blocks is more than or equal to 99 percent.
3. The preparation method of the safe and environment-friendly silicon-strontium inoculant as claimed in claim 1, wherein the preparation method comprises the following steps: according to the requirement that the strontium content in the industrial common strontium-silicon inoculant is usually less than or equal to 2 percent, the metal strontium block added into the ladle each time does not exceed 2 percent.
4. The preparation method of the safe and environment-friendly silicon-strontium inoculant as claimed in claim 1, wherein the preparation method comprises the following steps: the strontium pressing device comprises a strontium pressing protective cover (1), a hoisting core rod (2) and a rigging shackle (3), wherein the strontium pressing protective cover (1) covers the opening of a ladle (5), a metal strontium block (4) is suspended on the lower end face of the hoisting core rod (2), the hoisting core rod (2) slides to penetrate through the strontium pressing protective cover (1) to press the metal strontium block (4) into the ladle (5), and the rigging shackle (3) is arranged at the top of the hoisting core rod (2) and is used for connecting external hoisting equipment (6).
5. The preparation method of the safe and environment-friendly silicon-strontium inoculant as claimed in claim 4, wherein the preparation method comprises the following steps: the strontium-pressing protective cover (1) is cast and molded by adopting heat-resistant cast iron, and a skirt edge is arranged at the periphery of the strontium-pressing protective cover (1); a conical through hole (11) for the hoisting core bar (2) to penetrate through is formed in the center of the strontium pressing protective cover (1); a circular reinforcing boss is arranged at the center of the strontium pressing protective cover (1), and the conical through hole (11) is positioned at the axis of the circular reinforcing boss.
6. The preparation method of the safe and environment-friendly silicon-strontium inoculant as claimed in claim 5, wherein the preparation method comprises the following steps: the hoisting core bar (2) comprises a core bar main body (21), a plurality of limit baffles (23), a strontium pressing disc (22) and a plurality of triangular reinforcing ribs (24) which play a role of guiding the hoisting core bar (2) and the strontium pressing protective cover (1), wherein the strontium pressing disc (22) is arranged at the lower end of the core bar main body (21), and a plurality of round holes (25) for penetrating iron wires for binding the strontium metal blocks are formed in the strontium pressing disc (22); a plurality of triangular reinforcing ribs (24) are uniformly welded at the joint of the strontium pressing disc (22) and the core rod main body (21); a plurality of limiting baffles (23) are uniformly distributed on the outer wall of the upper part of the core rod main body (21); the top of the core rod main body (21) is welded with a hoisting lug (26).
7. The preparation method of the safe and environment-friendly silicon-strontium inoculant as claimed in claim 6, wherein the preparation method comprises the following steps: the external hoisting equipment (6) is a bridge crane, and a hook of the bridge crane is connected with the rigging shackle (3) through a chain (7); the chain (7) adopts a mining high-strength round-link chain, one end of the round-link chain is connected with the rigging shackle (3), and the other end of the round-link chain is connected with a lifting hook of the bridge crane.
8. The preparation method of the safe and environment-friendly silicon-strontium inoculant as claimed in claim 7, wherein the preparation method comprises the following steps: step 4, adding the metal strontium block in the step 1 into a foundry ladle through a strontium pressing device, and comprising the following steps:
step 4.1) assembling the strontium pressing device;
step 4.2) binding and suspending the metal strontium block (4) which needs to be pressed into the ladle (5) below the circular strontium pressing disc (22) by using an iron wire;
step 4.3), hoisting the strontium pressing device to the upper part of the ladle (5) by external hoisting equipment (6), and reducing the strontium pressing device; the strontium pressing protective cover (1) firstly covers the opening of the ladle (5), and a hoisting core rod (2) of the strontium pressing device continuously descends to press the metal strontium block (4) into the low-aluminum silicon iron melt (8) in the ladle (5);
and 4.4) after the melting reaction of the metal strontium block (4) is finished, hoisting the hoisting core rod (2) of the strontium pressing device by external hoisting equipment (6), and removing the strontium pressing device.
9. The preparation method of the safe and environment-friendly silicon-strontium inoculant as claimed in claim 1, wherein the preparation method comprises the following steps: and 6, finishing primary casting when the thickness of the inoculant mold ingot is less than 100 mm.
10. The preparation method of the safe and environment-friendly silicon-strontium inoculant as claimed in claim 1, wherein the preparation method comprises the following steps: and 6, hoisting the ladle by the travelling crane, and manually rotating a rotating hand wheel on the ladle for casting.
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