CN117824357A - Method for improving furnace opening process of centralized smelting furnace - Google Patents

Abstract

The present invention discloses a method for improving the opening process of a centralized smelting furnace, which belongs to the technical field of steel smelting, including ignition before loading, and setting the temperature of the melting chamber of the smelting furnace to 755-800°C, the temperature of the aluminum liquid insulation chamber to 750±10°C, and the temperature of the aluminum water outlet to ≤740°C; during the melting process and subsequent refining, multiple slag removals are performed; when the charge is leveled, a layer of covering agent is evenly sprinkled into the furnace to fully cover the melt; when all the charge is leveled, it is fully stirred; the aluminum liquid in the insulation chamber is transferred to the refining furnace through a transfer ladle as soon as possible for refining. The present invention solves the pinhole problem of aluminum products from three aspects: reducing the source of pinhole problem initiators, reducing the fusion of pinhole problem initiators into aluminum liquid, and removing pinhole problem initiators in aluminum liquid, thereby achieving a diversified control effect on the pinhole degree of aluminum products, and effectively solving the problem of unqualified pinhole degree of products in the early stage of the centralized smelting furnace opening process.

Description

A method for improving the opening process of a centralized smelting furnace

Technical Field

The invention mainly relates to the technical field of steel smelting, and in particular to a method for improving the furnace opening process of a centralized smelting furnace.

Background technique

Pinholes are the most serious defects among all defects of aluminum products. The size and number of pinholes have a decisive impact on the moisture resistance, gas barrier and light shielding of aluminum and its composite materials. In the production process of aluminum alloy products, the pinhole problem has always troubled major companies, especially aluminum alloy automobile cylinder heads, whose large surface pinholes are so serious that the scrap rate is as high as more than 50%. In addition, about 30% of aluminum alloy automobile cylinder heads are scrapped due to pinholes.

Centralized smelting furnace is a device that melts aluminum and aluminum raw materials into qualified aluminum alloy melt. It is suitable for centralized smelting and centralized liquid supply in large aluminum alloy casting workshops. It has the advantages of high efficiency, low energy consumption, and small combustion loss. During the implementation of the original process, the pinhole degree of the product cast by the aluminum liquid smelted in the first 6-12 hours of each furnace opening is ≥3 levels, and the pinhole degree of the product returns to normal after 12 hours.

Summary of the invention

The technical solution of the present invention aims at the technical problem that the existing technical solution is too single, and provides a solution that is significantly different from the existing technology. It mainly provides a method for improving the centralized smelting furnace start-up process, which is used to solve the technical problem of unqualified pinhole degree of the early products in the existing centralized smelting furnace start-up process mentioned in the above background technology.

The technical solution adopted by the present invention to solve the above technical problems is:

A method for improving the opening process of a centralized smelting furnace, comprising the following contents:

(1) First ignite, set the melting chamber temperature of the smelting furnace, the temperature of the aluminum liquid insulation chamber and the temperature of the aluminum tapping nozzle. The melting chamber temperature of the smelting furnace is set to 755-800°C, the temperature of the aluminum liquid insulation chamber is set to 750±10°C, and the temperature of the aluminum tapping nozzle is set to ≤740°C; then load the materials;

(2) During the smelting process, the melting chamber and the holding chamber of the smelting furnace are cleaned once per shift. The melting chamber is cleaned after 2-4 bags of slag cleaning agent are left to stand for 20 minutes. When a certain amount of aluminum liquid is melted in the holding chamber, the slag removal work is carried out every 4-5 hours. The aluminum liquid in the holding chamber is transferred to the refining furnace through the transfer ladle as soon as possible for refining. When the charge is leveled, a layer of covering agent is evenly sprinkled into the furnace to fully cover the melt. The amount of the covering agent is 2.1-2.5 kg/t. When the charge is completely leveled, it is fully stirred to accelerate melting and cool down the local charge to prevent local overheating.

(3) After sampling and analysis, the composition is adjusted in the smelting furnace according to the alloy composition standard based on the analysis results before the furnace, and the alloy can be taken out of the furnace only after the composition is qualified; the additives added for composition adjustment must ensure a melting temperature of more than 720°C and a melting time of not less than 30 minutes;

(4) After the melt is refined and the surface slag is removed, the molten metal is poured into the static furnace. The temperature is strictly controlled during the converter. The melt is fully stirred before the converter and the melt temperature is accurately measured. The converter melt temperature is 755-765°C. After the converter, the spout and runner are cleaned in time.

(5) Before stopping the furnace, all slag in the melting chamber and the holding chamber must be cleaned. Use 4 packs of slag cleaning agent and let it stand for 20 minutes before cleaning the slag.

Furthermore, in content (1), preparation work should be done before loading: all iron tools that come into direct contact with the aluminum liquid should be cleaned, and then preheated and dried after coating; and the limit switches and the position of the feeder on the feeding device should be checked to ensure that they are in their original positions.

Furthermore, the charging operation in content (1) is as follows: first open the melting chamber door and place a layer of aluminum ingots on the bottom of the melting chamber, and then use the charging device to automatically charge; when charging, first load small pieces or recycled materials, then load aluminum ingots and large pieces in the middle, and finally load the intermediate alloy; the intermediate alloy with a low melting point and easy oxidation is loaded in the middle and lower layers; the loaded charge is evenly distributed in the molten pool to prevent it from being overweight; the height of the charging car is 50 mm lower than the highest position of the car, and the charge is put into the furnace at one time as much as possible.

Furthermore, the recycled materials do not use casting seams, burrs, aluminum chips and ladle oxide scale.

Furthermore, a gas collecting device for collecting waste gas from fuel combustion is pre-installed at the centralized smelting furnace, and a gas purification device is installed at the exhaust end of the gas collecting device. The gas collecting device and the gas purification device are started before ignition to purify the waste gas generated by fuel combustion.

Furthermore, the sampling spoon in content (3) should be heated before sampling, and ensure that the sampling spoon is clean and undamaged; the melt temperature during sampling is 730-760℃, and the melt should be thoroughly stirred before sampling to ensure uniform composition; when sampling, use a clean sampling spoon to quickly analyze the sample near the middle of the molten pool and the middle of the melt depth before taking the furnace.

Furthermore, the additive added for the composition adjustment in content (3) is at least one of Fe agent, Mn agent, intermediate alloy Al-Si, and intermediate alloy Al-Cu.

Furthermore, after the aluminum liquid is transferred into the transfer ladle, a slag removal agent is sprinkled into it, and it is deeply stirred to remove the slag ash; after the refining temperature is controlled at 720-740°C, a small amount of slag removal agent is sprinkled on the surface for secondary slag removal.

Furthermore, the residence time after refining in content (4) cannot be too long, and the waiting time for casting cannot exceed 0.5 hours. If it exceeds 0.5 hours, hydrogen testing must be performed again and it can only be used after passing the test.

Furthermore, in content (5), the aluminum liquid level in the furnace is lowered to a very low level before the furnace is shut down, so that the amount of solid aluminum formed in the furnace is relatively small. In this way, during the cooling process after the furnace is shut down, less heat is lost in the molten groove, and the cooling speed of the upper part of the molten groove is not too fast.

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

The present invention ignites first and then charges, and preheats the centralized smelting furnace first, which can remove residual moisture and some impurities in the smelting furnace, and can remove moisture and some impurities brought into the charge during the charging process, thereby reducing the hydrogen source and impurity source that cause the pinhole problem of aluminum products, and alleviating the pinhole defect problem of aluminum products from the source.

In the optimized solution of the present invention, a gas collecting device and a gas purification device are provided for collecting and cleaning the exhaust gas from fuel combustion. The gas collecting device and the gas purification device are started before ignition to purify the exhaust gas generated by the fuel combustion, thereby removing the hydrogen source and impurities brought by the exhaust gas from the fuel combustion, thereby further reducing the sources of hydrogen and impurities that cause pinhole problems in aluminum products.

The present invention performs multiple slag cleaning in the melting process and subsequent refining, which can reduce the impurity content in the aluminum liquid; when the furnace charge is leveled, a layer of covering agent is evenly sprinkled into the furnace to fully cover the melt, which can prevent the gas containing hydrogen and the like from continuing to contact with the aluminum liquid, thereby achieving the effect of preventing the increase of dissolved hydrogen; when the furnace charge is completely leveled, it is fully stirred to accelerate melting, and the local furnace charge is cooled to prevent local overheating, which can also play the effect of reducing dissolved hydrogen.

The refining process of the present invention mainly involves degassing, dehydrogenation and impurity removal, and removes most of the hydrogen and impurities in the aluminum liquid that cause pinhole problems. In combination with the above points, the present invention solves the pinhole problem of aluminum products from three aspects: reducing the source of pinhole problem triggers - reducing the fusion of pinhole problem triggers into aluminum liquid - removing pinhole problem triggers in aluminum liquid, achieving a diversified control effect on the pinhole degree of aluminum products, and being able to efficiently guarantee the quality of aluminum liquid discharge, effectively solving the problem of unqualified pinhole degree of products in the early stage of the centralized smelting furnace opening process.

The melting chamber temperature of the smelting furnace set in the present invention is set to 755-800°C, and the temperature of the aluminum liquid insulation chamber is set to 750±10°C, which are higher than the set temperatures in the prior art and can accelerate the melting rate of the aluminum liquid. In addition, the present invention can effectively solve the problem of increased dissolved hydrogen in the aluminum liquid due to temperature increase by reducing the source of pinhole problem initiators - reducing the fusion of pinhole problem initiators into the aluminum liquid - removing the pinhole problem initiators in the aluminum liquid through three means.

The present invention will be explained in detail below with reference to the accompanying drawings and specific embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a process flow chart of the present invention.

Detailed ways

To facilitate understanding of the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings, but the present invention can be implemented in different forms and is not limited to the embodiments described in the text. On the contrary, these embodiments are provided to make the content disclosed in the present invention more thorough and comprehensive.

It should be noted that when an element is referred to as being "fixed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used in this article are for illustrative purposes only.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly connected by technicians in the technical field to which the present invention belongs. The terminology used in the specification of the present invention is for the purpose of describing specific embodiments and is not intended to limit the present invention. The term "and/or" used herein includes any and all combinations of one or more related listed items.

Example 1

Please refer to Figure 1, a production process of aluminum liquid casting products includes the following furnace opening process:

Ignition work: First open the main valve of natural gas and high-pressure air, and confirm whether the pressure of natural gas and high-pressure air is normal. Close the power switches, turn on the combustion fan, and after the combustion fan pressure is normal, turn on the burner. Be sure to open both furnace doors before ignition;

When igniting, supply air first and then supply oil. When stopping the fire, stop the oil first and then stop the air. The order cannot be reversed. During the process of oil supply and ignition, no one is allowed to stand or operate in front of the furnace door. When the furnace is heated from cold, first light firewood or oil cotton yarn in the furnace, and then supply air and oil. It is strictly forbidden to supply oil first and then ignite. After each ignition failure, the oil valve should be closed first, and the oil mist in the furnace should be blown clean by ventilation before the second ignition operation. The order is the same as above. Prevent the procedure from being reversed to avoid burns caused by the furnace explosion. After the ignition is successful, adjust the flame and air-oil ratio of the burner to make the flame normal and burn fully.

Preparation before loading: All iron tools that come into direct contact with aluminum liquid must be cleaned before use, and preheated and dried after coating. Set the melting chamber temperature of the smelting furnace, the temperature of the aluminum liquid insulation chamber, and the temperature of the aluminum water outlet. The melting chamber temperature of the smelting furnace is set to 755-800℃, the temperature of the aluminum liquid insulation chamber is set to 750±10℃, and the temperature of the aluminum water outlet is ≤740℃. Check to ensure that the limit switches and the position of the feeder on the feeding device are in the original position.

Charging: Before charging, open the furnace door of the melting chamber and manually lay a layer of aluminum ingots on the bottom of the melting chamber to protect the refractory material at the bottom of the furnace, and then use the charging device to automatically charge. The correct charging depends on the nature and state of the added charge, and should also take into account the fastest melting speed, the least burning loss and accurate chemical composition control. When charging, first load small pieces or recycled materials (casting seams, burrs, aluminum chips and ladle oxide scales, etc. shall not be used as recycled materials), aluminum ingots and large pieces in the middle, and finally the master alloy. The master alloy with a melting point that is easy to oxidize is loaded in the middle and lower layers. The loaded charge should be evenly distributed in the molten pool to prevent eccentricity. Small pieces or recycled materials are loaded in the lower layer of the molten pool, which can reduce burning loss and protect the furnace body from direct impact and damage by large pieces. Some master alloys have high melting points, such as Al-Ni and Al-Mn alloys, which have melting points of 750-800℃. They are placed in the upper layer. Since the temperature in the upper part of the furnace is high, it is easy to melt and there is sufficient time for diffusion, so that the master alloy is evenly distributed, which is conducive to the composition control of the melt.

The loading height should be 50mm lower than the highest position of the loading car. If the charge is loaded flat, the melting speed of each part will be similar, which can prevent local metal overheating caused by excessive weight. The charge should be put into the furnace at one time as much as possible. Adding the charge twice or more times will increase non-metallic inclusions and gas content.

Melting: The melting chamber and holding chamber of the smelting furnace are deslagging once per shift. The melting chamber is deslagging after 2-4 packs of deslagging agent are left standing for 20 minutes. When a certain amount of aluminum liquid is melted in the holding chamber, deslagging is performed every 4-5 hours. The aluminum liquid in the holding chamber is transferred to the refining furnace through the transfer ladle as soon as possible for refining; during the smelting process, when the charge is leveled, a layer of covering agent is evenly sprinkled into the furnace to fully cover the melt. The amount of the covering agent is 2.1-2.5Kg/t. When all the charge is leveled, start to stir it fully to accelerate melting, and cool down the local charge to prevent local overheating;

The sampling spoon should be heated before sampling, and ensure that the sampling spoon is clean and undamaged. The melt temperature during sampling is 730-760℃. The melt should be thoroughly stirred before sampling to ensure uniform composition. The sample must be representative. When sampling, use a clean sampling spoon to quickly analyze the sample in front of the furnace near the middle of the molten pool and the middle of the melt depth. According to the results of the pre-furnace analysis, the composition is adjusted according to the alloy composition standard in the smelting furnace, and it can only be taken out of the furnace after the composition is qualified. Additives added for composition adjustment, such as Fe agent, Mn agent, intermediate alloys Al-Si, Al-Cu, etc., must ensure a melting time of more than 720℃ and not less than 30 minutes;

The aluminum alloy smelting process requires the aluminum liquid to be modified. The modification is carried out before refining. Before the aluminum liquid is transferred from the melting furnace to the transfer ladle, a modifier is added to the bottom of the furnace. It is added in the form of an alloy, and the modifier element is not added directly. Aluminum strontium alloy rods are often used as modifiers. Sr is a long-term modifier, and the modification time can last for 6 to 8 hours, which makes the coarse flaky silicon refined into fine tissues, further improving the mechanical properties. This modification effect is better than the modification effect added in the melting furnace, which can reduce burning and decay. After Sr is melted at the bottom of the furnace, it is stirred evenly by a rotary degasser to reduce segregation. The aluminum liquid after Sr modification absorbs hydrogen faster and produces more pinholes.

Refining: After the aluminum liquid is transferred to the transfer ladle, sprinkle the slag remover, stir deeply, and beat out the slag ash. Measure whether the aluminum liquid temperature can reach the refining temperature. If the temperature is too high, it is necessary to add recycled materials to cool it down. If the temperature is too low, it is necessary to power on to heat it up. The refining temperature is controlled at 720-740℃. After the adjustment is qualified, sprinkle a small amount of slag remover on the surface. Degassing refining is mainly for degassing and dehydrogenation. Since most of the slag inclusions have been removed by the first deep stirring, but there is still a small amount of aluminum slag inside, a small amount of slag remover is sprinkled in the second time to remove the aluminum slag.

Converter: After the melt is refined and the surface slag is removed, when the temperature is appropriate, the molten metal can be poured into the static furnace to prepare for casting. The residence time after refining cannot be too long, and the waiting time for casting cannot exceed 0.5 hours. If it exceeds 0.5 hours, hydrogen needs to be re-tested and it can only be used after passing the test;

The temperature should be strictly controlled during the converter. The melt should be fully stirred before the converter and the melt temperature should be accurately measured. The measuring couple should be placed in the middle and lower part of the melt depth for measurement. The converter melt temperature is 755-765℃. Before the converter, the sealing condition of the pouring furnace launder should be checked; the liquid level should be controlled during the converter to avoid aluminum liquid overflow. After the converter, the launder and launder should be cleaned in time.

Shutdown: Before stopping the furnace, all slag in the melting chamber and the insulation chamber must be cleaned. Use 4 packs of slag remover and let it stand for 20 minutes before cleaning. For some large pieces of slag, the slag should be cleaned after the temperature reaches 850℃. After stopping the furnace, the furnace door and discharge port and other outlets that are prone to heat leakage should be closed. It is best to close the flue valve as well. When stopping the furnace, the aluminum liquid level in the furnace is lowered to a very low position, and the amount of solid aluminum formed in the furnace is small. In this way, during the cooling process of stopping the furnace, less heat is lost in the melting groove, and the cooling speed of the upper part of the melting groove will not be too fast.

Compared with the original process, the pinhole degree of the products cast by the aluminum liquid in the present embodiment after the furnace is opened is less than level 2 each time the aluminum liquid is cast in the early stage of the furnace opening, and the products cast by the aluminum liquid during the whole process of the furnace opening are qualified.

Example 2

The difference between this embodiment and embodiment 1 is that:

A gas collecting device for collecting waste gas from fuel combustion is pre-installed at the centralized smelting furnace, and a gas purification device is installed at the exhaust end of the gas collecting device. The gas collecting device and the gas purification device are started before ignition to purify the waste gas generated by fuel combustion.

The rest is the same as in Example 1.

The above is an exemplary description of the present invention in combination with the accompanying drawings. It is obvious that the specific implementation of the present invention is not limited to the above-mentioned method. As long as such non-substantial improvements are made by adopting the method concept and technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims (10)

1. A method for improving the open process of a centralized smelting furnace is characterized in that: the method comprises the following steps:

(1) Firstly, igniting, and setting the temperature of a melting chamber of a smelting furnace, the temperature of an aluminum liquid heat preservation chamber and the temperature of an aluminum discharge nozzle, wherein the temperature of the melting chamber of the smelting furnace is set to 755-800 ℃, the temperature of the aluminum liquid heat preservation chamber is set to 750+/-10 ℃, and the temperature of the aluminum discharge nozzle is set to be less than or equal to 740 ℃; recharging;

(2) In the smelting process, slag is removed once per shift in a smelting chamber and a heat preservation chamber of the smelting furnace, and slag removal is carried out after 2-4 bags of slag remover are used for the smelting chamber and are kept stand for 20 min; when a certain amount of aluminum liquid is melted in the heat preservation chamber, deslagging is carried out every 4-5 hours; transferring the aluminum liquid in the heat preservation chamber into a refining furnace for refining as soon as possible through a transfer ladle; when the furnace burden is melted, uniformly scattering a layer of covering agent into the furnace to cover the melt on the whole surface, wherein the dosage of the covering agent is 2.1-2.5Kg/t, and when the furnace burden is melted on the whole surface, the furnace burden starts to be fully stirred so as to accelerate the melting, and the local furnace burden is cooled to prevent local overheating;

(3) After sampling analysis, according to the analysis result in front of the furnace, carrying out component adjustment in the smelting furnace according to the alloy component standard, and discharging after the components are qualified; the additives added for ingredient adjustment must ensure a melting temperature above 720 ℃ and a melting time of not less than 30 minutes;

(4) When the melt is subjected to refining treatment and surface scum is scraped off, the metal melt is infused into a standing furnace, the temperature is strictly controlled during the converter, the melt is fully stirred before the converter, the temperature of the melt is accurately measured, and the temperature of the melt in the converter is 755-765 ℃; timely cleaning a flow port and a launder after the converter;

(5) All slag in the melting chamber and the holding chamber must be cleaned before the furnace is shut down.

2. A method of improving a furnace opening process of a centralized smelting furnace as claimed in claim 1, wherein: the content (1) is ready for preparation before loading: cleaning all iron tools in direct contact with the aluminum liquid, and preheating and drying after coating; checking to ensure that the positions of limit switches and skip cars on the feeding device are at original positions.

3. A method of improving a furnace opening process of a centralized smelting furnace as claimed in claim 1, wherein: the loading operation of the content (1) is as follows: firstly, opening a furnace door of a melting chamber, paving a layer of aluminum ingot at the bottom of the melting chamber, and then, automatically feeding by using a feeding device; when the material is filled, small blocks or furnace returns are firstly filled, an aluminum ingot and a large block are filled in the middle, and finally, intermediate alloy is filled; the intermediate alloy with the melting point easy to oxidize is arranged on the middle lower layer; the charged furnace burden is uniformly distributed in the molten pool, so that the weight deviation is prevented; the height of the charging and loading vehicle is 50mm lower than the highest position of the skip car, and the furnace burden is charged as once as possible.

4. A method of improving a furnace opening process of a centralized smelting furnace according to claim 3, wherein: the furnace return material does not adopt casting shawl, burrs, aluminum scraps and ladle oxide skin.

5. A method of improving a furnace opening process of a centralized smelting furnace as claimed in claim 1, wherein: heating the sampling spoon before sampling in the content (3), and ensuring that the sampling spoon is clean and free from damage; the temperature of the melt during sampling is 730-760 ℃, and the melt is thoroughly stirred before sampling to ensure that the components are uniform; during sampling, a clean sampling spoon is used for rapidly analyzing a sample before taking the furnace at the middle part close to the middle part of the molten pool and the melt depth.

6. A method of improving a furnace opening process of a centralized smelting furnace as claimed in claim 1, wherein: the additive added for component adjustment in the content (3) is at least one of Fe agent, mn agent, intermediate alloy Al-Si and intermediate alloy Al-Cu.

7. A method of improving a furnace opening process of a centralized smelting furnace as claimed in claim 1, wherein: after the aluminum liquid is transferred into a rotary casting ladle, a slag remover is scattered, and slag ash is discharged after deep stirring; and after the refining temperature is controlled to be 720-740 ℃, a small amount of slag remover is scattered on the surface to carry out secondary slag removal.

8. A method of improving a furnace opening process of a centralized smelting furnace as claimed in claim 1, wherein: the residence time after refining in the content (4) cannot be too long, the time waiting for casting cannot exceed 0.5 hour, the hydrogen is required to be re-detected for more than 0.5 hour, and the alloy can be used after being qualified.

9. A method of improving a furnace opening process of a centralized smelting furnace as claimed in claim 1, wherein: in the content (1), a gas collecting device for collecting fuel combustion exhaust gas is arranged at a centralized smelting furnace in advance, a gas purifying device is arranged at an exhaust end of the gas collecting device, and the gas collecting device and the gas purifying device are started before ignition so as to purify the exhaust gas generated by fuel combustion.

10. A method of improving a furnace opening process of a centralized smelting furnace as claimed in claim 1, wherein: in item (5), the level of aluminum in the furnace is lowered to a very low level prior to the shutdown, and the amount of solid aluminum formed in the furnace is small.