CN115044738A - Method for improving recycling utilization level of stainless steel slag of electric furnace - Google Patents
Method for improving recycling utilization level of stainless steel slag of electric furnace Download PDFInfo
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- CN115044738A CN115044738A CN202210515767.2A CN202210515767A CN115044738A CN 115044738 A CN115044738 A CN 115044738A CN 202210515767 A CN202210515767 A CN 202210515767A CN 115044738 A CN115044738 A CN 115044738A
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- 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
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/52—Manufacture of steel in electric furnaces
- C21C5/54—Processes yielding slags of special composition
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- C—CHEMISTRY; METALLURGY
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- C21B3/00—General features in the manufacture of pig-iron
- C21B3/04—Recovery of by-products, e.g. slag
- C21B3/06—Treatment of liquid slag
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Abstract
The invention relates to the technical field of comprehensive utilization of metallurgical resources, in particular to a method for improving the resource utilization level of electric furnace stainless steel slag. The method specifically comprises the following steps: the molten stainless steel slag produced normally in an electric furnace is filled into a slag pot, modifier is added into the slag pot, and the stainless steel slag and the modifier are uniformly mixed by means of stirring and the like to form molten mixed slag. And slowly cooling the modified stainless steel slag to improve the enrichment degree and stability of chromium elements in a spinel phase, so as to obtain the stainless steel slag with chromium stably enriched in the spinel phase. And (3) separating the treated stainless steel slag to separate the top stainless steel slag from the whole stainless steel slag to obtain high-chromium slag and low-chromium slag. The invention realizes the enrichment of chromium in a large amount in the spinel phase, and the iron element is added into the formation of the spinel phase, so that the grain size of the spinel phase is changed to be larger, and the spinel phase can be recovered by magnetic separation due to the entering of the iron, thereby effectively improving the resource utilization rate of the stainless steel slag.
Description
Technical Field
The invention relates to the technical field of comprehensive utilization of metallurgical resources, in particular to a method for improving the resource utilization level of electric furnace stainless steel slag.
Background
The iron and steel industry, as an industry with foundation and strategic in national economy, has already had a very large production scale and a very high production level through years of uninterrupted development. Therefore, the stainless steel industry in China is well developed. By 2020, the yield of stainless steel in China reaches 3013.9 ten thousand tons. Such huge stainless steel production is accompanied by the consumption of a large amount of resources and energy sources caused by the production and the generation of industrial wastes (commonly called "three wastes", i.e., waste gas, waste water, waste residues). The current production of stainless steel slag per ton of stainless steel has exceeded 600 million tons per year, and is increasing year by year.
The stainless steel slag is a byproduct in the stainless steel smelting process, and can be used as a good foundation material mainly used as a roadbed material, a concrete aggregate, a building material raw material, an iron-making sintering material and the like due to excellent strength performance. However, the stainless steel slag contains a small amount of hexavalent chromium, which is extremely toxic and easily dissolved out of the stainless steel slag, and pollutes the natural environment in which people rely on living. At present, domestic stainless steel production enterprises only recover valuable metals such as iron, chromium, nickel and the like through ore grinding-ore dressing processes, and tailings are low in recovery rate and are mostly piled in a slag yard or landfill. This is not only wasteful of resources but also a potential threat to the environment. Therefore, in order to achieve better resource utilization of stainless steel slag and better economic efficiency, the risk of chromium elution must be minimized.
Aiming at the problem of dissolving out hexavalent chromium in stainless steel slag, experts and scholars at home and abroad do a great deal of research work. The invention patent CN 110357459A provides a method for controlling the risk of chromium contamination in chromium-containing steel slags, in which it is impossible to completely eliminate the presence of free CaO during the actual operation, so that part of the CaCr is produced 2 O 4 Wherein, trivalent chromium can be oxidized into hexavalent chromium under certain conditions, and the hexavalent chromium can pollute the environment after being dissolved out with severe toxicity. The invention patent CN 106517834A provides a method for harmless treatment of stainless steel slag by molten blast furnace slag at high temperature, which is mainly to obtain glassy slag by water quenching, and to store chromium in stable glassy slag. However, the risk of chromium elution in the glassy state increases with time, and the production cost is high. At present, the ideal chromium dissolution control measure is to perform mineral phase regulation and control on the phase in the stainless steel slag by adding a modifier, controlling the oxygen partial pressure, adjusting the cooling system and the like, and the main purpose is to enable a large amount of chromium elements to exist in a stable spinel phase, so that the risk of chromium dissolution can be effectively reduced. Because the phase types in the stainless steel slag are complex, the spinel phase and other phases are difficult to realize high-efficiency separation, so that the crystal grain size of the spinel phase is increased, and the separation efficiency of the spinel can be effectively improved. Since chromium still exists in the stainless steel slag in the resource utilization process, and the chromium resource is wasted.
In view of the above, there is a need to design a method for improving the recycling level of the stainless steel slag of the electric furnace to solve the above problems.
Disclosure of Invention
The invention aims to solve the potential risk of chromium element, the problem of spinel grain size growth and the problem of difficult recovery of chromium resource during the resource utilization of the stainless steel slag.
In order to realize the purpose, the invention provides a horizontal method for improving the resource utilization of the electric furnace stainless steel slag.
A method for improving the resource utilization level of electric furnace stainless steel slag comprises the following steps:
(1) loading molten stainless steel slag normally produced by an electric furnace into a slag pot, and uniformly mixing the slag with a first temperature and a modifier in a non-oxidizing atmosphere to carry out modification treatment to obtain modified slag;
(2) slowly cooling the modified slag obtained in the step (1) to a temperature below a second temperature in a non-oxidizing atmosphere to improve the enrichment degree and stability of chromium in a spinel phase and obtain stainless steel slag with chromium stably enriched in the spinel phase, wherein the top layer of the slag is high-chromium slag with high chromium content and is a main aggregation area of the spinel phase; the chromium element content of the rest parts except the top layer of the slag is extremely low, namely the chromium slag part is low, and more RO phases exist;
(3) shunting the stainless steel slag obtained in the step (2) by using shunting equipment, wherein in the process of pouring the stainless steel slag out of the slag pot, shunting treatment is carried out on the slag by using a shunting plate of the shunting equipment, so that the high-chromium slag part on the top layer of the stainless steel slag is separated from the whole body and is recovered;
in the horizontal method for improving the resource utilization of the stainless steel slag of the electric furnace, the non-oxidizing atmosphere is the atmosphere for avoiding Cr 3+ And Fe 2+ Is oxidized into Cr 6+ And Fe 3+ Of the atmosphere (c). Examples of the gas contained in the non-oxidizing atmosphere include non-oxidizing gases such as nitrogen, argon, and helium.
The horizontal method for improving the resource utilization of the stainless steel slag of the electric furnace also comprises the modified stainless steel slag obtained after the treatment of the step (2), wherein when the subsequent stainless steel slag treatment process in the actual production process is a water-cooling treatment process with a tank, the operation of the step (3) is not required, the slag in a slag tank is cooled to room temperature after the water-cooling treatment with the tank is completed, partial slag with the top accounting for 1/8-1/6 of the whole volume is taken, a high-chromium slag part with high chromium content is recovered, the high-chromium slag part is combined with the recovery treatment equipment of the existing factory, and the spinel containing chromium is recovered from the stainless steel slag in a magnetic separation or reselection mode; and (3) combining the low-chromium slag part with the recovery processing equipment of the existing factory, and recovering the iron element in the stainless steel slag in a magnetic separation or gravity separation mode.
The horizontal method for improving the resource utilization of the stainless steel slag of the electric furnace also comprises a post-treatment step (4), because the separation is carried out in the dumping process, the subsequent stainless steel slag treatment process is not influenced, the high chromium slag and the low chromium slag obtained in the step (3) can be treated by a roller method, a hot stuffiness method, a tray hot splashing water quenching method or a hot box hot splashing method, and the like, the treated pulverized stainless steel slag is combined with the high chromium slag part of the recovery treatment equipment of the existing factory, and the chromium-containing spinel is recovered from the stainless steel slag in a magnetic separation or gravity separation mode; and (3) combining the low-chromium slag part with the recovery processing equipment of the existing factory, and recovering the iron element in the stainless steel slag in a magnetic separation or gravity separation mode.
In the horizontal method for improving the resource utilization of the electric furnace stainless steel slag, in the step (1), the stainless steel slag mainly comprises CaO and MgO by weight 40-50%, and SiO 2 20～30wt％，MnO 2～3wt％，Al 2 O 3 5～10wt％，FeO 8～22wt％，Cr 2 O 3 2～10wt％，w(CaO)/w(SiO 2 )≤2.5。
In the horizontal method for improving the resource utilization of the electric furnace stainless steel slag, in the step (1), the first temperature is 1500-1650 ℃.
In the method for improving the level of resource utilization of the electric furnace stainless steel slag, in the step (1), the modifier is one or more of iron oxide, scrap iron, iron scale or iron dust, and the main components of the modifier are FeO and Fe 2 O 3 And Fe 3 O 4 The addition amount of the stainless steel slag is 1-25% of the mass of the stainless steel slag.
In the method for improving the level of the resource utilization of the electric furnace stainless steel slag, the modifier is FeO and Fe 2 O 3 、Fe 3 O 4 At least one of the above components, wherein the addition amount of the at least one component is 1-25% of the mass of the stainless steel slag.
In the horizontal method for improving the resource utilization of the electric furnace stainless steel slag, in the step (2), the slow cooling rate is less than or equal to 30 ℃/min.
In the horizontal method for improving the resource utilization of the electric furnace stainless steel slag, in the step (2), the second temperature is 1200-1400 ℃.
In the step (2), the high-chromium slag part with high chromium content at the top of the molten slag accounts for 1/8-1/6 of the whole volume of the molten slag.
In the step (3), the splitter main body comprises a main splitter plate and an auxiliary splitter plate, the main splitter plate is a trapezoidal hollow plate body, the auxiliary splitter plate is provided with two plate bodies with the same shape and is arranged in the main splitter plate, the size of the whole splitter plate can be enlarged by drawing from the hollow main splitter plate, the main splitter plate and the auxiliary splitter plate are provided with slag discharging grooves, and two sides of each slag discharging groove are provided with fixing devices.
The reposition of redundant personnel equipment utilizes fixing device to be fixed in slag ladle jar mouth department, the flow distribution plate is trapezoidal slag ladle inner wall of closely laminating, make the slag ladle at the deslagging in-process, the slag can be flowed by the lower slag notch that flow distribution plate and slag ladle inner wall formed, also can follow the last slag notch that flow distribution plate and slag ladle inner wall formed and flow, the slag quantity is different in the slag ladle, the vice flow distribution plate of accessible adjustment changes the position that the reposition of redundant personnel equipment was located, lower slag notch base is the slag ladle inner wall, it is the flow distribution plate to go up the slag notch base, it is by the slag notch to go up the slag notch dress in jar mouth department. And after the temperature of the molten slag reaches 1200-1400 ℃, the fluidity of the molten slag is reduced, the high chromium slag part on the top layer of the molten slag still stays on the top layer of the molten slag and moves forwards in the pouring process, and when the high chromium slag part flows through the flow divider, the high chromium slag part flows out from the upper slag discharging port, and the low chromium slag part flows out from the lower slag discharging port, so that the separation and recovery of the high chromium slag part and the stainless steel slag are integrally completed.
In the step (3), the shunting equipment is made of refractory materials, and comprises 1/4-2/3 of the length of a main shunting plate as the height of a slag pot, 1/5-3/5 of the width of the bottom of the shunting equipment as the diameter of a mouth of the slag pot, and 1/5-3/5 of the width of the top of the shunting equipment as the diameter of the slag pot at the top of the main shunting plate; the length of the auxiliary splitter plate is consistent with that of the main splitter plate, and the width of the auxiliary splitter plate is 1/2 of the main splitter plate; fixing device and slag notch.
In the step (3), the width of the splitter plate can be lengthened or shortened by adjusting the auxiliary splitter plate according to the slag storage amount in the slag tank, so that the position of the splitter device can be adjusted.
In the horizontal method for improving the resource utilization of the stainless steel slag of the electric furnace, in the step (3), the shunting equipment is stably fixed in the slag pot through a fixing device; the high-chromium slag part at the top separated in the pouring process can be externally connected with a stainless steel slag collecting device through a slag discharging groove or directly flows into the stainless steel slag collecting device in the pouring process through prolonging the slag discharging groove.
Compared with the prior art, the invention has the beneficial effects that:
(1) according to the method for improving the recycling utilization level of the stainless steel slag of the electric furnace, the molten stainless steel slag is modified, and a proper cooling system is adopted, so that a large amount of chromium elements in the stainless steel slag are stably enriched in a spinel phase, and only a small amount of chromium elements exist in a small RO phase. The modifier added in the invention is the iron-containing oxide, so the modifier can effectively promote the growth of the spinel phase, and the iron element participates in the generation of the spinel phase, so the spinel phase can be recovered by magnetic separation, and simultaneously, the addition of the iron-containing oxide enables a large amount of iron to exist in the RO phase, so the iron and chromium in the RO phase can be effectively recovered by magnetic separation. Therefore, the growth of spinel is effectively promoted, and favorable conditions are created for magnetically separating iron and chromium elements.
(2) After the treatment by the method for improving the recycling utilization level of the stainless steel slag of the electric furnace, the phase of the obtained stainless steel slag is distributed in a spatial structure, the top layer is a region with a large amount of spinel phases, and the top layer is mainly high-chromium slag with high chromium content because chromium elements are stably enriched in the spinel phases in a large amount; the rest of the slag except the top layer of the slag is low-chromium slag with low chromium content, and only a small amount of chromium element exists in the RO phase, so that the iron and chromium elements can be effectively recovered through magnetic separation, and the stainless steel slag with extremely low chromium content can be obtained through the magnetic separation. The spatial structure distribution of the phase of the stainless steel slag obtained by treatment is beneficial to resource recovery of each component in the stainless steel slag, and the resource utilization rate of the stainless steel slag is improved.
(3) According to the method for improving the recycling utilization level of the stainless steel slag of the electric furnace, the high chromium slag part with high chromium content at the top layer can be effectively separated from the stainless steel slag integrally by using the shunting equipment, and chromium elements can be recovered from the separated high chromium slag with high chromium content in a targeted manner after the stainless steel slag treatment process of a factory; after a large amount of low-chromium slag with low chromium content is separated out and is subjected to stainless steel slag treatment process of a factory, the low-chromium slag can be treated and utilized according to common steel slag. The problem that chromium in the stainless steel slag is difficult to recover and not completely recovered can be effectively solved through the separation treatment of the stainless steel slag, the waste of chromium resources is reduced, and the stainless steel slag can be recycled.
(4) The method for improving the recycling utilization level of the stainless steel slag of the electric furnace provided by the invention has the advantages that the investment for processing the stainless steel slag can be greatly reduced without independently building a factory, the energy consumption in the processing process is low, and the risk of secondary pollution caused by recycling the stainless steel slag can be obviously reduced.
(5) The stainless steel slag treated by the method for improving the resource utilization level of the electric furnace stainless steel slag provided by the invention can meet the resource utilization standard, and can be applied to the production of microcrystalline glass, ceramic materials, roadbed materials, building materials and mineralized and stored CO 2 And the like.
Description of the drawings:
FIG. 1 is a scanning electron microscope image of a stainless steel slag modified by FeO modifier added in an amount of 10% by mass based on the mass of the stainless steel slag obtained in example 1 of the present invention;
FIG. 2 is an X-ray diffraction chart of stainless steel slag modified by FeO modifier added in an amount of 10% by mass based on the mass of the stainless steel slag obtained in example 1 of the present invention;
FIG. 3 is a scanning electron microscope image of the stainless steel slag modified by FeO modifier added in an amount of 10% by mass based on the mass of the stainless steel slag obtained in example 1 of the present invention.
Fig. 4 is a structural view of the stainless steel slag diversion apparatus of the present invention, wherein (1) is a front view, (2) is a top view, (3) is a side view, (4) is a front view of a rear side of the extended sub-diversion plate, (5) is a rear top view of the extended sub-diversion plate, and (6) is a rear side view of the extended sub-diversion plate.
Fig. 5 shows a structure diagram of the stainless steel slag diversion apparatus of the present invention installed in a slag pot, wherein (1) is a front view, (2) is a top view, (3) is a side view, (4) is a front view after an expansion sub-diversion plate, (5) is a top view after the expansion sub-diversion plate, and (6) is a side view after the expansion sub-diversion plate.
FIG. 6 is a schematic diagram of the present invention utilizing stainless steel slag diverting equipment to separate chromium-containing stainless steel slag from the top.
In the figure, 1-main splitter plate, 2-auxiliary splitter plate, 3-fixing device, 4-slag discharging groove, 5-slag pot, 6-splitter device, 7-spinel phase gathering area and 8-slag.
Detailed Description
For a better understanding of the technical features, objects, and advantages of the present invention, reference will now be made to the following detailed description of the embodiments of the present invention taken in conjunction with the accompanying drawings, which are set forth to illustrate, but are not to be construed to limit the scope of the present invention.
The test methods described in the following examples are all conventional methods unless otherwise specified; the reagents and materials are commercially available, unless otherwise specified.
The method for improving the resource utilization level of the electric furnace stainless steel slag provided by the invention is described by the specific embodiment below; in the following examples, stainless steel slag was divided by cutting, and the grain size of spinel phase was calculated and analyzed by scanning electron microscope and IPP6.0 analysis software.
In the following examples, "stainless steel smelting slag" is electric furnace slag, and its main components are CaO, MgO, SiO 2 、MnO、Al 2 O 3 、FeO、Cr 2 O 3 And the like.
In the following embodiments, the main flow distribution device body includes a main flow distribution plate 1 and an auxiliary flow distribution plate 2, the main flow distribution plate 1 is a trapezoidal hollow plate, the auxiliary flow distribution plate 2 has two plates with the same shape and is disposed in the main flow distribution plate 1, the size of the overall flow distribution plate can be enlarged by drawing out the hollow main flow distribution plate 1, the main flow distribution plate 1 and the auxiliary flow distribution plate 2 are provided with slag outlets 4, and fixing devices 3 are disposed on two sides of the slag outlets 4. The flow dividing equipment is made of refractory materials, the length of the main flow dividing plate 1 is 1/2 of the height of the slag pot, the width of the bottom of the main flow dividing plate is 1/3 of the diameter of the mouth of the slag pot, and the width of the top of the main flow dividing plate is 1/3 of the diameter of the position of the slag pot at which the top of the main flow dividing plate is located; the length of the sub-splitter plate 2 is the same as that of the main splitter plate, and the width of the sub-splitter plate is 1/2 of the main splitter plate.
The reposition of redundant personnel equipment utilizes fixing device 3 to be fixed in slag ladle jar mouth department, and the flow distribution plate is trapezoidal slag ladle inner wall that closely laminates, makes the slag ladle at the in-process of falling the sediment, and the slag can be flowed by the lower slag notch that flow distribution plate and slag ladle inner wall formed, also can follow the last slag notch that flow distribution plate and slag ladle inner wall formed and flow, and the slag gauge is different in the slag ladle, and the vice flow distribution plate 2 of accessible adjustment changes the position that the reposition of redundant personnel equipment located, and lower slag notch base is the slag ladle inner wall, and last slag notch base is the flow distribution plate, and last slag notch is equipped with slag notch 4 in jar mouthful department.
The shunting equipment can lengthen or shorten the width of the shunting plate by adjusting the auxiliary shunting plate 2 according to the slag storage amount in the slag ladle, thereby realizing the position adjustment of the shunting equipment.
The shunting equipment is stably fixed in the slag pot through a fixing device 3; the high-chromium slag part at the top separated in the dumping process can be externally connected with a stainless steel slag collecting device at the slag discharging groove 4 through the slag discharging groove 4 or directly flows into the stainless steel slag collecting device in the dumping process through prolonging the slag discharging groove.
Example 1
Step 1: after the stainless steel slag produced by the electric furnace is normally discharged from the furnace, the main chemical components of the stainless steel slag comprise 40 wt% of CaO, 10 wt% of MgO and 10 wt% of SiO 2 27wt％，MnO 3wt％，Al 2 O 3 6wt％，FeO 8wt％，Cr 2 O 3 5 wt%. The molten stainless steel slag normally produced by an electric furnace is filled into a slag pot, the slag pot is simulated by a crucible which is reduced in proportion, a shunting device is installed, the atmosphere is non-oxidizing atmosphere, the temperature of molten slag is 1600 ℃, and the non-oxidizing atmosphere is argon atmosphere. And then adding an FeO modifier with the mass being 10% of that of the stainless steel slag into the molten slag, and stirring to uniformly mix the stainless steel slag and the FeO additive to form molten mixed slag, thereby obtaining the modified molten slag.
Step 2: the obtained modified slag is slowly cooled from 1600 ℃ to 1300 ℃ at a cooling rate of 3.5 ℃/min under the condition of non-oxidizing atmosphere.
And step 3: pouring the molten slag out of the slag tank, carrying out shunting treatment by using shunting equipment, carrying out water quenching treatment, and then rapidly cooling to room temperature to obtain two parts of stainless steel slag.
And 4, step 4: and carrying out magnetic separation and reselection treatment on the two parts of the obtained stainless steel slag to recover iron and chromium resources.
The obtained slag sample was subjected to SEM-EDS and XRD detection analysis, and the results are shown in FIGS. 1 and 2. The main phases of the modified stainless steel slag are a multiflower rose pyroxene phase, a glass phase, an RO phase and a spinel phase. Except a small amount of chromium element existing in a small amount of RO phase, the chromium element is almost completely enriched in the spinel phase, and the selective enrichment of chromium in the spinel phase is basically realized. As shown in FIG. 3, the phases of the stainless steel slag are spatially distributed, the spinel phase is mainly distributed at the top of the slag, the RO phase and the glass phase are mainly distributed at the middle and lower parts of the slag, and the multiflower rose pyroxene phase is distributed at each part of the slag. The grain size of the spinel phase is calculated and analyzed by IPP6.0 analysis software, the average grain size of the spinel phase is 12.8 mu m, and compared with an unmodified treatment result under the same experimental condition, the average grain size of the spinel phase is increased by 66.23%, so that the size of the spinel phase is effectively increased. The stainless steel slag with high chromium content on the top of the stainless steel slag obtained by separation is combined by magnetic separation and gravity separation, and the recovery rate of the chromium component is 29 percent. The recovery rate of the iron component in the stainless steel slag is 47 percent. The leaching concentration of chromium in the low-chromium slag part at the bottom of the stainless steel slag obtained by separation is lower than 0.01 mg/L.
Example 2
Step 1: after the stainless steel slag produced by the electric furnace is normally discharged, the main chemical components of the stainless steel slag comprise 40 wt% of CaO, 10 wt% of MgO and 10 wt% of SiO 2 27wt％，MnO 3wt％，Al 2 O 3 6wt％，FeO 8wt％，Cr 2 O 3 5 wt%. The molten stainless steel slag normally produced by an electric furnace is filled into a slag pot, the atmosphere is non-oxidizing atmosphere, the temperature of molten slag is 1600 ℃, and the non-oxidizing atmosphere is argon atmosphere. Then adding Fe accounting for 10 percent of the mass of the stainless steel slag into the molten slag 2 O 3 Modifier, stirring stainless steel slag and Fe 2 O 3 And uniformly mixing the additives to form molten mixed slag, thereby obtaining the modified molten slag.
Step 2: the obtained modified slag is slowly cooled from 1600 ℃ to 1300 ℃ at a cooling rate of 3.5 ℃/min under the condition of non-oxidizing atmosphere.
And step 3: and (3) rapidly cooling the slag to room temperature after water quenching treatment to obtain the modified stainless steel slag.
And 4, step 4: and scraping a part of the cooled whole stainless steel slag, the top of which accounts for 1/6 of the whole volume, to obtain two parts of the stainless steel slag.
And performing SEM-EDS and XRD detection analysis on the obtained slag sample. The main phases of the modified stainless steel slag are a multiflower rose pyroxene phase, a glass phase, an RO phase and a spinel phase. Except a small amount of chromium element existing in a small amount of RO phase, the chromium element is almost completely enriched in the spinel phase, and the selective enrichment of chromium in the spinel phase is basically realized. The various phases in the stainless steel slag are distributed according to space, the spinel phase is mainly distributed on the top of the slag, the RO phase and the glass phase are mainly distributed in the middle and the lower part of the slag, and the multiflower rose pyroxene phase is distributed in each part of the slag. The grain size of the spinel phase is calculated and analyzed by IPP6.0 analysis software, the average grain size of the spinel phase is 8.9 mu m, and compared with the unmodified treatment result under the same experimental condition, the average grain size of the spinel phase is increased by 15.58 percent, and the size of the spinel phase is increased. The leaching concentration of chromium in the part of the low-chromium slag at the bottom, which is left after the stainless steel slag at the top is scraped, is lower than 0.01 mg/L.
Example 3
Step 1: after the stainless steel slag produced by the electric furnace is normally discharged, the main chemical components of the stainless steel slag comprise 40 wt% of CaO, 10 wt% of MgO and 10 wt% of SiO 2 27wt％，MnO 3wt％，Al 2 O 3 6wt％，FeO 8wt％，Cr 2 O 3 5 wt%. The molten stainless steel slag normally produced by an electric furnace is filled into a slag pot, the atmosphere is non-oxidizing atmosphere, the temperature of molten slag is 1600 ℃, and the non-oxidizing atmosphere is argon atmosphere. Then adding Fe accounting for 10 percent of the mass of the stainless steel slag into the molten slag 3 O 4 Modifier, stirring stainless steel slag and Fe 3 O 4 And uniformly mixing the additives to form molten mixed slag, thereby obtaining the modified molten slag.
Step 2: the obtained modified slag is slowly cooled from 1600 ℃ to 1300 ℃ at a cooling rate of 3.5 ℃/min under the condition of non-oxidizing atmosphere.
And 3, step 3: and (3) rapidly cooling the slag to room temperature after water quenching treatment to obtain the modified stainless steel slag.
And 4, step 4: and scraping a part of the cooled whole stainless steel slag, the top of which accounts for 1/6 of the whole volume, to obtain two parts of the stainless steel slag.
And performing SEM-EDS and XRD detection analysis on the obtained slag sample. The main phases of the modified stainless steel slag are a multiflower rose pyroxene phase, a glass phase, an RO phase and a spinel phase. Except a small amount of chromium element existing in a small amount of RO phase, the chromium element is almost completely enriched in the spinel phase, and the selective enrichment of chromium in the spinel phase is basically realized. The various phases in the stainless steel slag are distributed according to space, the spinel phase is mainly distributed on the top of the slag, the RO phase and the glass phase are mainly distributed in the middle and the lower part of the slag, and the multiflower rose pyroxene phase is distributed in each part of the slag. The grain size of the spinel phase is calculated and analyzed by IPP6.0 analysis software, the average grain size of the spinel phase is 9.1 mu m, and compared with an unmodified treatment result under the same experimental condition, the average grain size of the spinel phase is increased by 18.18%, and the size of the spinel phase is increased. The leaching concentration of chromium in the part of the low-chromium slag at the bottom, which is left after the stainless steel slag at the top is scraped, is lower than 0.01 mg/L.
Example 4
Step 1: after the stainless steel slag produced by the electric furnace is normally discharged, the main chemical components of the stainless steel slag comprise 40 wt% of CaO, 10 wt% of MgO and 10 wt% of SiO 2 27wt％，MnO 3wt％，Al 2 O 3 6wt％，FeO 8wt％，Cr 2 O 3 5 wt%. Charging molten stainless steel slag normally produced by an electric furnace into a slag tank, simulating the slag tank by a crucible which is reduced in proportion, and installing a shunting device, wherein the slag tank is in a non-oxidizing atmosphere, the temperature of molten slag is 1600 ℃, and the non-oxidizing atmosphereAn argon atmosphere. And then adding an FeO modifier with the mass being 5 percent of that of the stainless steel slag into the molten slag, and stirring to uniformly mix the stainless steel slag and the FeO modifier to form molten mixed slag, thereby obtaining the modified molten slag.
Step 2: the obtained modified slag is slowly cooled from 1600 ℃ to 1300 ℃ at a cooling rate of 3.5 ℃/min under the condition of non-oxidizing atmosphere.
And step 3: pouring the molten slag out of the slag tank, carrying out shunting treatment by using shunting equipment, carrying out water quenching treatment, and then rapidly cooling to room temperature to obtain two parts of stainless steel slag.
And performing SEM-EDS and XRD detection analysis on the obtained slag sample. The main phases of the modified stainless steel slag are a multiflower rose pyroxene phase, a glass phase, an RO phase and a spinel phase. Except a small amount of chromium element existing in a small amount of RO phase, the chromium element is almost completely enriched in the spinel phase, and the selective enrichment of chromium in the spinel phase is basically realized. The stainless steel slag has various phase distributed spatially, spinel phase distributed mainly in the top of the slag, RO phase and glass phase distributed mainly in the middle and lower part of the slag, and rose pyroxene phase distributed in all parts of the slag. The grain size of the spinel phase is calculated and analyzed by IPP6.0 analysis software, the mean grain size of the spinel phase is 9.7 mu m, and compared with the unmodified treatment result under the same experimental condition, the mean grain size of the spinel phase is increased by 25.97 percent, and the size of the spinel phase is increased. The leaching concentration of chromium in the low-chromium slag at the bottom of the stainless steel slag is lower than 0.01 mg/L.
Comparative example 1
Step 1: after the stainless steel slag produced by the electric furnace is normally discharged from the furnace, the main chemical components of the stainless steel slag comprise 40 wt% of CaO, 10 wt% of MgO and 10 wt% of SiO 2 27wt％，MnO 3wt％，Al 2 O 3 6wt％，FeO 8wt％，Cr 2 O 3 5 wt%. The molten stainless steel slag normally produced by an electric furnace is filled into a slag pot, the atmosphere is non-oxidizing atmosphere, the temperature of molten slag is 1600 ℃, and the non-oxidizing atmosphere is argon atmosphere.
Step 2: and (3) rapidly cooling the slag to room temperature after water quenching treatment to obtain the stainless steel slag.
And performing SEM-EDS and XRD detection analysis on the obtained slag sample. The main phases of the stainless steel slag are a rose pyroxene phase, a glass phase and a spinel phase. The spinel phase is mainly distributed on top of the slag. The grain size of the spinel phase was calculated and analyzed using IPP6.0 analysis software, and the mean grain size of the spinel phase was 5.4 μm.
Compared with the example 1, the process of the comparative example is quenched at 1600 ℃, the average size of the obtained spinel phase is only 5.4 μm and is smaller than 12.8 μm obtained in the example 1, and the fact that the stainless steel slag is slowly cooled to 1300 ℃ for quenching through controlling the cooling system in the example 1 is proved to be beneficial to the growth of the spinel phase.
Comparative example 2
Step 1: after the stainless steel slag produced by the electric furnace is normally discharged, the main chemical components of the stainless steel slag comprise 40 wt% of CaO, 10 wt% of MgO and 10 wt% of SiO 2 27wt％，MnO 3wt％，Al 2 O 3 6wt％，FeO 8wt％，Cr 2 O 3 5 wt%. The molten stainless steel slag normally produced by an electric furnace is filled into a slag tank, the slag tank is in a non-oxidizing atmosphere, the slag temperature is 1600 ℃, and the non-oxidizing atmosphere is argon atmosphere.
And 2, step: the obtained slag is slowly cooled from 1600 ℃ to 1300 ℃ at a cooling rate of 3.5 ℃/min under the condition of non-oxidizing atmosphere.
And step 3: and (3) rapidly cooling the slag to room temperature after water quenching treatment to obtain the stainless steel slag.
And 4, step 4: and scraping a part of the cooled whole stainless steel slag, the top of which accounts for 1/6 of the whole volume, to obtain two parts of the stainless steel slag.
And performing SEM-EDS and XRD detection analysis on the obtained slag sample. The main phases of the stainless steel slag comprise a multiflower rose pyroxene phase, a glass phase, an RO phase and a spinel phase. Except a small amount of chromium element existing in a small amount of RO phase, the chromium element is almost completely enriched in the spinel phase, and the selective enrichment of chromium in the spinel phase is basically realized. The various phases in the stainless steel slag are distributed according to space, the spinel phase is mainly distributed on the top of the slag, the RO phase and the glass phase are mainly distributed in the middle and the lower part of the slag, and the multiflower rose pyroxene phase is distributed in each part of the slag. The grain size of the spinel phase was calculated and analyzed using IPP6.0 analysis software, and the mean grain size of the spinel phase was 7.7 μm.
Compared with example 1, the process of the comparative example has no added iron-containing modifier, and the average size of the spinel phase is only 7.7 μm and is smaller than 12.8 μm obtained in example 1, which proves that the addition of FeO as the modifier in example 1 is more beneficial to the growth of the spinel phase.
Claims (10)
1. A method for improving the resource utilization level of electric furnace stainless steel slag is characterized in that: the method comprises the following steps:
(1) loading molten stainless steel slag normally produced by an electric furnace into a slag pot, and uniformly mixing the slag with a first temperature and a modifier in a non-oxidizing atmosphere to carry out modification treatment to obtain modified slag;
(2) slowly cooling the modified slag obtained in the step (1) to a temperature below a second temperature in a non-oxidizing atmosphere to improve the enrichment degree and stability of chromium in a spinel phase and obtain stainless steel slag with chromium stably enriched in the spinel phase, wherein the top layer of the slag is high-chromium slag with high chromium content and is a main aggregation area of the spinel phase; the chromium element content of the rest parts except the top layer of the slag is extremely low, namely the chromium slag part is low, and more RO phases exist;
(3) shunting the stainless steel slag obtained in the step (2) by using shunting equipment, wherein slag is shunted by a shunting plate of the shunting equipment in the process of pouring the stainless steel slag out of the slag tank, so that the top-layer high-chromium slag part of the stainless steel slag is separated and recovered from the whole;
wherein the non-oxidizing atmosphere is to avoid Cr 3+ And Fe 2+ Is oxidized into Cr 6+ And Fe 3+ Of the atmosphere (c).
2. The method of claim 1, wherein: in the step (1), the main components of the stainless steel slag comprise 40-50 wt% of CaO and MgO and 40-50 wt% of SiO 2 20～30wt％，MnO 2～3wt％，Al 2 O 3 5～10wt％，FeO 8～22wt％，Cr 2 O 3 2～10wt％，w(CaO)/w(SiO 2 )≤2.5。
3. The method of claim 1, wherein: in the step (1), the first temperature is 1500-1650 ℃; the modifier is one or more of iron oxide, scrap iron, iron scale or iron dust, and the main components of the modifier are FeO and Fe 2 O 3 And Fe 3 O 4 The addition amount of the stainless steel slag is 1-25% of the mass of the stainless steel slag; or the modifier is FeO or Fe 2 O 3 、Fe 3 O 4 At least one of them, the adding amount is 1-25% of the stainless steel slag.
4. The method of claim 1, wherein: in the step (2), the slow cooling rate is less than or equal to 30 ℃/min; the second temperature is 1200-1400 ℃; the high-chromium slag part with high chromium content at the top of the slag is a part of the slag top occupying 1/8-1/6 of the whole volume.
5. The method of claim 1, wherein: when the subsequent stainless steel slag treatment process in the actual production process is a water cooling treatment process with a tank, the step (3) is omitted, the water cooling treatment with the tank is completed, the slag in the slag tank is cooled to room temperature, partial slag with the top occupying 1/8-1/6 of the whole volume is scraped so as to recover a high-chromium slag part with high chromium content, the high-chromium slag part is combined with the recovery treatment equipment of the existing factory, and chromium-containing spinel is recovered from the stainless steel slag in a magnetic separation or gravity separation mode; and (3) combining the low-chromium slag part with the recovery processing equipment of the existing factory, and recovering the iron element in the stainless steel slag in a magnetic separation or gravity separation mode.
6. The method of claim 1, wherein: the method comprises a post-treatment step (4), because separation is carried out in the pouring process, the subsequent stainless steel slag treatment process is not influenced, the high-chromium slag and the low-chromium slag obtained in the step (3) can be treated by a roller method, a hot stuffiness method, a tray hot splashing water quenching method or a hot box hot splashing method, the treated pulverized stainless steel slag is combined with the recovery treatment equipment of the existing factory, and the chromium-containing spinel is recovered from the stainless steel slag in a magnetic separation or gravity separation mode; and (3) combining the low-chromium slag part with the recovery processing equipment of the existing factory, and recovering the iron element in the stainless steel slag in a magnetic separation or gravity separation mode.
7. The method of claim 1, wherein: in the step (3), the splitter main body comprises a main splitter plate (1) and an auxiliary splitter plate (2), the main splitter plate (1) is a trapezoidal hollow plate, the auxiliary splitter plate (2) is provided with two plate bodies with the same shape and is arranged in the main splitter plate (1), the size of the whole splitter plate can be enlarged by drawing from the hollow main splitter plate (1), the main splitter plate (1) and the auxiliary splitter plate (2) are provided with slag discharging grooves (4), and two sides of each slag discharging groove (4) are provided with fixing devices (3);
the reposition of redundant personnel equipment utilizes fixing device (3) to be fixed in slag ladle tank mouth department, and the flow distribution plate is trapezoidal slag ladle inner wall that closely laminates, makes the slag ladle at the in-process of falling the sediment, and the slag can be flowed by the lower row's cinder notch that flow distribution plate and slag ladle inner wall formed, also can follow the last row's cinder notch that flow distribution plate and slag ladle inner wall formed and flow, and the slag quantity is different in the slag ladle, and the position that the reposition of redundant personnel equipment was located is changed to the vice flow distribution plate of accessible adjustment (2), and lower row's cinder notch base is the slag ladle inner wall, and it is the flow distribution plate to go up the cinder notch base, goes up the cinder notch and adorn by slag notch (4) in tank mouth department.
8. The method of claim 1, wherein: in the step (3), the flow dividing equipment is made of refractory materials, the length of the main flow dividing plate (1) is 1/4-2/3 of the height of the slag pot, the width of the bottom of the main flow dividing plate is 1/5-3/5 of the diameter of the mouth of the slag pot, and the width of the top of the main flow dividing plate is 1/5-3/5 of the diameter of the position of the slag pot on the top of the main flow dividing plate; the length of the auxiliary splitter plate (2) is consistent with that of the main splitter plate, and the width of the auxiliary splitter plate is 1/2 of the main splitter plate.
9. The method of claim 1, wherein: in the step (3), the width of the splitter plate can be lengthened or shortened by adjusting the auxiliary splitter plate (2) according to the slag storage amount in the slag tank, so that the position of the splitter device can be adjusted.
10. The method of claim 1, wherein: in the step (3), the shunting equipment is stably fixed in the slag pot through a fixing device (3); the high-chromium slag part at the top separated in the pouring process can be externally connected with a stainless steel slag collecting device at the slag discharging groove (4) through the slag discharging groove (4) or directly flows into the stainless steel slag collecting device in the pouring process through prolonging the slag discharging groove.
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| JP2002192125A (en) * | 2001-10-12 | 2002-07-10 | Kawasaki Steel Corp | Reduction treatment method for chromium oxide- containing substance |
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