CN114561540B - Method for efficiently extracting, separating and recycling chromium in stainless steel slag - Google Patents
Method for efficiently extracting, separating and recycling chromium in stainless steel slag Download PDFInfo
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- CN114561540B CN114561540B CN202210387761.1A CN202210387761A CN114561540B CN 114561540 B CN114561540 B CN 114561540B CN 202210387761 A CN202210387761 A CN 202210387761A CN 114561540 B CN114561540 B CN 114561540B
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- 239000002893 slag Substances 0.000 title claims abstract description 175
- 239000010935 stainless steel Substances 0.000 title claims abstract description 122
- 229910001220 stainless steel Inorganic materials 0.000 title claims abstract description 122
- 239000011651 chromium Substances 0.000 title claims abstract description 48
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 title claims abstract description 40
- 229910052804 chromium Inorganic materials 0.000 title claims abstract description 37
- 238000000034 method Methods 0.000 title claims abstract description 32
- 238000004064 recycling Methods 0.000 title claims abstract description 19
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 31
- 229910045601 alloy Inorganic materials 0.000 claims abstract description 21
- 239000000956 alloy Substances 0.000 claims abstract description 21
- 238000000926 separation method Methods 0.000 claims abstract description 14
- 238000001816 cooling Methods 0.000 claims abstract description 9
- 238000012216 screening Methods 0.000 claims abstract description 9
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 8
- 229910000599 Cr alloy Inorganic materials 0.000 claims abstract description 5
- 239000000788 chromium alloy Substances 0.000 claims abstract description 5
- 238000009628 steelmaking Methods 0.000 claims abstract description 5
- 239000000654 additive Substances 0.000 claims abstract description 3
- 230000000996 additive effect Effects 0.000 claims abstract description 3
- 239000002699 waste material Substances 0.000 claims description 22
- 238000005520 cutting process Methods 0.000 claims description 19
- 239000003607 modifier Substances 0.000 claims description 18
- 238000010438 heat treatment Methods 0.000 claims description 17
- 238000006722 reduction reaction Methods 0.000 claims description 17
- 229910021420 polycrystalline silicon Inorganic materials 0.000 claims description 12
- WGLPBDUCMAPZCE-UHFFFAOYSA-N Trioxochromium Chemical compound O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 claims description 11
- 229910000423 chromium oxide Inorganic materials 0.000 claims description 11
- 229910021419 crystalline silicon Inorganic materials 0.000 claims description 7
- 230000008569 process Effects 0.000 claims description 7
- 239000002002 slurry Substances 0.000 claims description 7
- 229910001610 cryolite Inorganic materials 0.000 claims description 5
- BTBUEUYNUDRHOZ-UHFFFAOYSA-N Borate Chemical compound [O-]B([O-])[O-] BTBUEUYNUDRHOZ-UHFFFAOYSA-N 0.000 claims description 4
- VVTSZOCINPYFDP-UHFFFAOYSA-N [O].[Ar] Chemical compound [O].[Ar] VVTSZOCINPYFDP-UHFFFAOYSA-N 0.000 claims description 4
- 229910052810 boron oxide Inorganic materials 0.000 claims description 4
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 claims description 4
- 229910001634 calcium fluoride Inorganic materials 0.000 claims description 4
- JKWMSGQKBLHBQQ-UHFFFAOYSA-N diboron trioxide Chemical compound O=BOB=O JKWMSGQKBLHBQQ-UHFFFAOYSA-N 0.000 claims description 4
- 238000010891 electric arc Methods 0.000 claims description 3
- 230000009467 reduction Effects 0.000 abstract description 16
- 230000001603 reducing effect Effects 0.000 abstract description 11
- 238000011084 recovery Methods 0.000 abstract description 7
- 239000003795 chemical substances by application Substances 0.000 abstract description 5
- 230000004048 modification Effects 0.000 abstract description 3
- 238000012986 modification Methods 0.000 abstract description 3
- 229910000831 Steel Inorganic materials 0.000 abstract description 2
- 238000003912 environmental pollution Methods 0.000 abstract description 2
- 230000005484 gravity Effects 0.000 abstract description 2
- 239000010959 steel Substances 0.000 abstract description 2
- 238000002844 melting Methods 0.000 abstract 1
- 230000008018 melting Effects 0.000 abstract 1
- QDOXWKRWXJOMAK-UHFFFAOYSA-N dichromium trioxide Chemical compound O=[Cr]O[Cr]=O QDOXWKRWXJOMAK-UHFFFAOYSA-N 0.000 description 12
- 239000000126 substance Substances 0.000 description 8
- 241001584775 Tunga penetrans Species 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- 238000004321 preservation Methods 0.000 description 7
- 229910004298 SiO 2 Inorganic materials 0.000 description 6
- 239000012535 impurity Substances 0.000 description 6
- 239000000203 mixture Substances 0.000 description 6
- 238000010606 normalization Methods 0.000 description 6
- 238000010079 rubber tapping Methods 0.000 description 6
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 4
- 239000004568 cement Substances 0.000 description 4
- 238000011946 reduction process Methods 0.000 description 4
- 238000007789 sealing Methods 0.000 description 4
- 238000004458 analytical method Methods 0.000 description 3
- JOPOVCBBYLSVDA-UHFFFAOYSA-N chromium(6+) Chemical compound [Cr+6] JOPOVCBBYLSVDA-UHFFFAOYSA-N 0.000 description 3
- 229910052710 silicon Inorganic materials 0.000 description 3
- 239000010703 silicon Substances 0.000 description 3
- 238000004846 x-ray emission Methods 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 229910004072 SiFe Inorganic materials 0.000 description 2
- 238000003723 Smelting Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 229910004261 CaF 2 Inorganic materials 0.000 description 1
- 229910000519 Ferrosilicon Inorganic materials 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000006260 foam Substances 0.000 description 1
- 230000008676 import Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 239000011863 silicon-based powder Substances 0.000 description 1
- 239000002910 solid waste Substances 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000003381 stabilizer Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 230000001988 toxicity Effects 0.000 description 1
- 231100000419 toxicity Toxicity 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B34/00—Obtaining refractory metals
- C22B34/30—Obtaining chromium, molybdenum or tungsten
- C22B34/32—Obtaining chromium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B5/00—General methods of reducing to metals
- C22B5/02—Dry methods smelting of sulfides or formation of mattes
- C22B5/04—Dry methods smelting of sulfides or formation of mattes by aluminium, other metals or silicon
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
- C22B7/001—Dry processes
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
- C22B7/04—Working-up slag
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Metallurgy (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Organic Chemistry (AREA)
- Geology (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- Treatment Of Steel In Its Molten State (AREA)
- Manufacture And Refinement Of Metals (AREA)
- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
Abstract
The invention belongs to the technical field of metallurgical resource recycling, and discloses a method for efficiently extracting, separating and recycling chromium in stainless steel slag. Comprising the following steps: 1) Adding a reducing agent and a modifying agent into the molten stainless steel slag, reducing chromium in the stainless steel slag, and adjusting the viscosity of the molten stainless steel slag; 2) Controlling the temperature to be more than 1450 ℃, performing melting treatment, preserving heat for 1-2h, and cooling to room temperature along with a furnace; 3) And crushing and screening the treated slag sample, and then separating by gravity separation to obtain alloy and tailings. The content of chromium in the alloy reaches more than 85%, the residual rate of chromium in the tailings is less than 1%, and the recovery rate of chromium in the stainless steel slag is 90-95%. The invention has the advantages that: the chromium in the steel slag is gathered through the modification of the stainless steel slag, the micro-carbon chromium alloy obtained after reduction can be returned to the steelmaking process as an alloy element additive, and the tailings can be returned to a stainless steel enterprise to be used as a slag former in the steelmaking process, so that the problems of environmental pollution of the stainless steel slag are solved, and the comprehensive utilization of resources is realized.
Description
Technical Field
The invention relates to a method for efficiently extracting, separating and recycling chromium in stainless steel slag, belonging to the technical field of metallurgical resource recycling.
Background
Stainless steel slag is waste generated in the stainless steel smelting process, and because the stainless steel slag contains more chromium, but chromium ore resources in China are extremely barren and depend on import in a large amount, the recovery value of the chromium resources in the stainless steel slag is high. Meanwhile, due to the large accumulation of the stainless steel slag, hexavalent chromium in the stainless steel slag has serious toxicity, so that the resource is wasted greatly and the environment is polluted.
At present, most of the recycling methods of stainless steel slag are common as follows: curing and sealing method, wet reduction method and dry reduction method. The solidifying and sealing method mainly adopts a stabilizer to seal the steel slag in a matrix, and the common matrix is cement, namely the common cement sealing method. The reducing agent, cement and stainless steel slag are mixed according to a certain proportion and then buried, so that the stainless steel slag is sealed in the cement. Obviously, the current solidification and sealing method does not recycle chromium resources in the stainless steel slag; wet reduction method: the method comprises the steps of dissolving the ground stainless steel slag by using an aqueous solution or an acid solution, and reducing hexavalent chromium in the stainless steel slag by using different reducing agents, wherein a large amount of wastewater is generated while chromium resources in the stainless steel slag are recovered, so that serious environmental pollution is caused; dry reduction method: under the high temperature condition, hexavalent chromium is reduced into trivalent chromium or even chromium simple substance by using a reducing agent. The dry reduction method mainly comprises a high-temperature carbon reduction method and a high-temperature ferrosilicon reduction method, and is characterized in that Cr 6+ is reduced into Cr 3+ or even Cr by using a reducing agent (C, si/SiFe and the like) at high temperature. The method has the advantages of fully utilizing the heat of the stainless steel smelting process, along with simple process and being capable of effectively recycling valuable metals such as Fe, cr, ni and the like in the slag. However, when C is used as a reducing agent, fe in the slag can be reduced to a lower level, but the CrO x content is still higher, and the foam slag generated in the reaction process has extremely uneven content. And the CO gas generated in the carbothermic reduction process is not friendly to the environment. When reducing agents such as Si/SiFe, al, mg, caC 2 are used, the influence of the reduction products on the reduction process and the cost problem need to be considered. If waste materials such as waste silicon powder in some industries are used as a reducing agent for treating chromium-containing solid waste, not only can the low cost and high efficiency of deep reduction be realized, but also the comprehensive utilization of secondary resources can be realized.
Disclosure of Invention
Aiming at the problems of environment unfriendly, high cost, unstable reduction effect and the like in the dry reduction process of the stainless steel slag, the invention aims to provide the method for reducing the stainless steel slag by adopting the dry reduction process: the method for efficiently and stably recycling chromium resources in the stainless steel slag is provided, the reduced chromium simple substance and the reducing agent silicon are aggregated and precipitated to form the micro-carbon chromium alloy, and the reduced tailings can be directly returned to a stainless steel enterprise to be used as a slag forming agent for recycling in the steelmaking process, so that the efficient recycling of the stainless steel slag is realized.
The invention achieves the aim by adopting the following technical scheme:
A method for efficiently extracting, separating and recycling chromium in stainless steel slag, wherein the stainless steel slag is stainless steel Electric Arc Furnace (EAF) slag or stainless steel argon oxygen furnace (AOD) slag with higher Cr content; adding one or more of boron oxide, borate, calcium fluoride or cryolite into the molten stainless steel slag as a modifier to reduce the viscosity of the molten stainless steel slag; one or more of solar-grade polycrystalline silicon cutting waste and crystalline silicon cutting waste slurry is used as a reducing agent, and the chromium simple substance generated after reduction can be smoothly gathered and deposited, so that the reduction effect is strong and the reduction effect is stable; then carrying out heat treatment on the molten stainless steel slag added with the reducing agent and the modifying agent; and (3) carrying out reselection separation on the stainless steel slag after heat treatment to obtain alloy and tailings.
Further, the invention provides a method for efficiently recycling chromium element in molten stainless steel slag by means of modification and reduction of the molten stainless steel slag, heat treatment of slag and separation by gravity separation, which comprises the following specific steps:
(1) When the stainless steel slag is discharged from the furnace, detecting the viscosity, the temperature and the chromium oxide content of the slag; in the deslagging process, a modifying agent and a reducing agent are added, the temperature is controlled to enable the viscosity of slag to be less than 1.0 Pa.S, and the stainless steel slag is fully and uniformly mixed with the modifying agent and the reducing agent by utilizing impact force generated in the deslagging process, so that slag is obtained;
the stainless steel slag is stainless steel electric arc furnace EAF slag or stainless steel argon oxygen furnace AOD slag with higher Cr content;
The modifier is one or more of boron oxide, borate, calcium fluoride or cryolite, and the total amount of the modifier is controlled to be not higher than 10 percent of the total weight of the stainless steel slag;
The reducing agent is one or more of solar-grade polycrystalline silicon cutting waste and crystalline silicon cutting waste slurry, wherein the content of Si in the solar-grade polycrystalline silicon cutting waste is 90-99wt.%; in the crystalline silicon cutting waste slurry, the Si content is 40-50wt.%;
The usage amount of the reducing agent is as follows: the mass of Si in the reducing agent is 1.0-2.0 times of the theoretical value of Si required by the silicon thermal reduction reaction of chromium oxide in the stainless steel slag to 2Cr 2O3+3Si＝4Cr+3SiO2;
(2) And (3) carrying out heat treatment on the slag obtained in the step (1).
The heat treatment equipment is equivalent to a refining furnace, bottom blowing gas stirring is adopted to uniformly stir the temperature and components of slag in the furnace, electrode heating is used for adjusting and controlling the slag heat preservation time, the stainless steel slag is ensured to be preserved for 1-2 hours at the temperature of over 1450 ℃, the stainless steel slag and the reducing agent solar grade polycrystalline silicon cutting waste are promoted to fully react, the heat treatment system can promote chromium oxide in the stainless steel slag to be fully reduced into chromium simple substance, and the subsequent separation effect is facilitated to be improved.
(3) And cooling the slag after heat treatment along with a furnace, crushing, screening, putting into a jigger, and carrying out reselection separation to obtain alloy and tailings. The micro-carbon chromium alloy is returned to steelmaking to be used as an alloy element additive, and tailings are returned to the stainless steel enterprises for internal recycling.
In the step (3), the content of Cr 2O3 in the separated tailings is below 1%.
The beneficial effects of the invention are as follows:
(1) The density of the molten stainless steel slag is between 2 and 3g/cm 3, the density of the chromium simple substance is 7.2g/cm 3, and the chromium can be aggregated and precipitated even if a modifier is not added in the aspect of density analysis, but practical experiments prove that under the condition that only the molten stainless steel slag and a reducing agent are added, the chromium cannot be aggregated and precipitated to be an alloy, and the analysis reasons are as follows: the viscosity of the molten stainless steel slag is too high, and the chromium simple substance generated after reduction cannot be aggregated. Therefore, in order to achieve the effect of chromium aggregation, precipitation and separation, the modifier is added, so that the viscosity of the molten stainless steel slag is reduced, the chromium simple substances in the sample are aggregated, precipitated and the alloy and slag are obviously separated after precipitation, and the purpose of effectively recycling chromium resources from the slag is achieved.
(2) The added reducing agent is solar-grade polycrystalline silicon cutting waste or crystalline silicon cutting waste slurry, the cost is low, and meanwhile, the reducing effect of silicon is better than that of the traditional carbon reducing agent, and the reducing effect is more stable.
(3) The modifier is one or more of boron oxide, borate, calcium fluoride or cryolite. Can effectively reduce the viscosity of the molten stainless steel slag, thereby gathering and precipitating the chromium simple substance.
(4) The total amount of the modifier is controlled to be not more than 10% of the total weight of the molten stainless steel slag. The addition of excessive modifier can not effectively reduce the residual chromium content of tailings, and simultaneously, the cost is increased. The viscosity of the stainless steel slag can achieve the best effect of recycling chromium resources in the stainless steel slag by adopting the proportion.
Drawings
FIG. 1 is a process flow diagram of the invention for efficiently recycling chromium resources in stainless steel slag.
FIG. 2 is a schematic flow chart of the recovery of chromium resources from stainless steel slag.
Detailed Description
The present invention and its effects are further described below with reference to specific embodiments and data.
Example 1:
(1) Taking stainless steel slag (EAF slag) of a certain stainless steel company in an electric furnace tapping stage, wherein the components mainly comprise SiO 2、CaO、MgO、Cr2O3, the rest impurity components are subjected to normalization treatment, and reducing agent solar grade polycrystalline silicon cutting waste (Si content is 98 wt.%) is added into the stainless steel slag, wherein the addition amount is 2.0 times of the amount required for reducing chromium oxide in the molten stainless steel slag; adding modifier B 2O3 with the addition amount of 6% of the total weight of the molten stainless steel slag to make the slag viscosity smaller than 1.0 Pa.S, so as to obtain 10kg of the total weight of the molten stainless steel slag. Example 1 the composition of the molten stainless steel slag is shown in table 1.
TABLE 1
(2) Carrying out heat treatment on the molten stainless steel slag obtained in the step (1), controlling the temperature of a slag pot to be more than 1450 ℃ and preserving heat for two hours to enable the slag to be fully and uniformly melted, and cooling to room temperature along with a furnace after heat preservation is finished to obtain final slag;
(3) Crushing and screening slag samples, putting the slag samples into a jigger, and carrying out reselection separation to obtain alloy and tailings.
Example 2:
(1) Taking stainless steel slag (EAF slag) of a certain stainless steel company in an electric furnace tapping stage, wherein the components mainly comprise SiO 2、CaO、MgO、Cr2O3, the rest impurity components are subjected to normalization treatment, and reducing agent solar grade polycrystalline silicon cutting waste (Si content is 98 wt.%) is added into the stainless steel slag, wherein the addition amount is 1.0 times of the amount required for reducing chromium oxide in the molten stainless steel slag; adding modifier B 2O3 with the addition amount of 6% of the total weight of the molten stainless steel slag to make the slag viscosity smaller than 1.0 Pa.S, so as to obtain 10kg of the total weight of the molten stainless steel slag. Example 2 the composition of the molten stainless steel slag is shown in table 2.
TABLE 2
(2) Carrying out heat treatment on the molten stainless steel slag obtained in the step (1), controlling the temperature of a slag pot to be more than 1450 ℃ and preserving heat for two hours to enable the slag to be fully and uniformly melted, and cooling to room temperature along with a furnace after heat preservation is finished to obtain final slag;
(3) Crushing and screening slag samples, putting the slag samples into a jigger, and carrying out reselection separation to obtain alloy and tailings.
Example 3
(1) Taking stainless steel slag (AOD slag) of a certain stainless steel company in an argon-oxygen furnace tapping stage, wherein the components mainly comprise SiO 2、CaO、MgO、Cr2O3, the rest impurity components are subjected to normalization treatment, and reducing agent solar grade polycrystalline silicon cutting waste (Si content is 98 wt.%) is added into the stainless steel slag, wherein the addition amount is 2.0 times of the amount required for reducing chromium oxide in the molten stainless steel slag; adding modifier B 2O3 with the addition amount of 6% of the total weight of the molten stainless steel slag to make the slag viscosity smaller than 1.0 Pa.S, so as to obtain 10kg of the total weight of the molten stainless steel slag. Example 3 the composition of the molten stainless steel slag is shown in table 3.
TABLE 3 Table 3
(2) Carrying out heat treatment on the molten stainless steel slag obtained in the step (1), controlling the temperature of a slag pot to be more than 1450 ℃ and preserving heat for two hours to enable the slag to be fully and uniformly melted, and cooling to room temperature along with a furnace after heat preservation is finished to obtain final slag;
(3) Crushing and screening slag samples, putting the slag samples into a jigger, and carrying out reselection separation to obtain alloy and tailings.
Example 4
(1) Taking stainless steel slag (EAF slag) of a certain stainless steel company in an electric furnace tapping stage, wherein the components mainly comprise SiO 2、CaO、MgO、Cr2O3, the rest impurity components are subjected to normalization treatment, and reducing agent solar grade polycrystalline silicon cutting waste (Si content is 98 wt.%) is added into the stainless steel slag, wherein the addition amount is 2.0 times of the amount required for reducing chromium oxide in the molten stainless steel slag; adding a modifier CaF 2, wherein the addition amount is 6% of the total weight of the molten stainless steel slag, so that the slag viscosity is less than 1.0 Pa.S, and the total weight of the molten stainless steel slag is 10kg. Example 4 the composition of the molten stainless steel slag is shown in table 4.
TABLE 4 Table 4
(2) Carrying out heat treatment on the molten stainless steel slag obtained in the step (1), controlling the temperature of a slag pot to be more than 1450 ℃ and preserving heat for two hours to enable the slag to be fully and uniformly melted, and cooling to room temperature along with a furnace after heat preservation is finished to obtain final slag;
(3) Crushing and screening slag samples, putting the slag samples into a jigger, and carrying out reselection separation to obtain alloy and tailings.
Example 5
(1) Taking stainless steel slag (EAF slag) of a certain stainless steel company in an electric furnace tapping stage, wherein the components mainly comprise SiO 2、CaO、MgO、Cr2O3, the rest impurity components are subjected to normalization treatment, and reducing agent solar grade polycrystalline silicon cutting waste (Si content is 98 wt.%) is added into the stainless steel slag, wherein the addition amount is 2.0 times of the amount required for reducing chromium oxide in the molten stainless steel slag; adding a modifier NaAl 3F6 (cryolite) into the molten stainless steel slag, wherein the addition amount is 6% of the total weight of the molten stainless steel slag, and the viscosity of the slag is less than 1.0 Pa.S, so as to obtain 10kg of the total weight of the molten stainless steel slag. Example 5 the composition of the molten stainless steel slag is shown in table 5.
TABLE 5
(2) Carrying out heat treatment on the molten stainless steel slag obtained in the step (1), controlling the temperature of a slag pot to be more than 1450 ℃ and preserving heat for two hours to enable the slag to be fully and uniformly melted, and cooling to room temperature along with a furnace after heat preservation is finished to obtain final slag;
(3) Crushing and screening slag samples, putting the slag samples into a jigger, and carrying out reselection separation to obtain alloy and tailings.
Example 6
(1) Taking stainless steel slag (EAF slag) of a certain stainless steel company in an electric furnace tapping stage, wherein the components mainly comprise SiO 2、CaO、MgO、Cr2O3, the rest impurity components are subjected to normalization treatment, and reducing agent crystalline silicon cutting waste slurry (Si content is 50 wt.%) is added into the stainless steel slag, wherein the addition amount is 2.0 times of the amount required for reducing chromium oxide in the molten stainless steel slag; adding modifier B 2O3 with the addition amount of 6% of the total weight of the molten stainless steel slag to make the slag viscosity smaller than 1.0 Pa.S, so as to obtain 10kg of the total weight of the molten stainless steel slag. Example 6 the composition of the molten stainless steel slag is shown in table 6.
TABLE 6
(2) Carrying out heat treatment on the molten stainless steel slag obtained in the step (1), controlling the temperature of a slag pot to be more than 1450 ℃ and preserving heat for two hours to enable the slag to be fully and uniformly melted, and cooling to room temperature along with a furnace after heat preservation is finished to obtain final slag;
(3) Crushing and screening slag samples, putting the slag samples into a jigger, and carrying out reselection separation to obtain alloy and tailings.
The tailings and alloys produced after the tests of the molten stainless steel slag in examples 1, 2, 3, 4, 5, 6 were subjected to component analysis by X-ray fluorescence spectroscopy (XRF), and the XRF results are shown in table 7.
TABLE 7
| Total weight of tailings (kg) | Cr 2O3 in the tailings | Total weight of alloy (kg) | Cr ratio (%) | |
| Example 1 | 8.83 | 0.78 | 1.04 | 88.88 |
| Example 2 | 8.75 | 1.02 | 0.83 | 87.49 |
| Example 3 | 9.86 | 0.19 | 0.065 | 88.54 |
| Example 4 | 8.65 | 0.72 | 1.13 | 89.65 |
| Example 5 | 8.91 | 0.74 | 1.01 | 87.98 |
| Example 6 | 8.81 | 0.71 | 1.07 | 87.68 |
Epsilon Cr was defined as the recovery of chromium element. m c1,mc2 represents the mass of tailings and alloy respectively. Omega Cr1,ωCr2 respectively represents the ratio of chromium element in the tailings and the alloy.
Recovery rate calculations were performed for examples 1,2, 3, 4, 5, and 6, and recovery rate results are shown in table 8.
TABLE 8
| Example 1 | Example 2 | Example 3 | Example 4 | Example 5 | Example 6 | |
| Recovery (%) | 95.14 | 92.24 | 81.78 | 95.96 | 95.16 | 95.38 |
The above embodiments are provided for illustrating the technical aspects of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principle and spirit of the present invention, the scope of which is defined by the appended claims and equivalents thereof.
Claims (3)
1. The method for efficiently extracting, separating and recycling chromium in the stainless steel slag is characterized by comprising the following steps of:
(1) When the stainless steel slag is discharged from the furnace, detecting the viscosity, the temperature and the chromium oxide content of the slag; in the deslagging process, adding a modifier and a reducing agent, controlling the temperature to ensure that the viscosity of slag is less than 1.0 Pa.S, and fully and uniformly mixing the stainless steel slag with the modifier and the reducing agent to obtain slag;
The modifier is one or more of boron oxide, borate, calcium fluoride or cryolite, and the total amount of the modifier is controlled to be not higher than 10 percent of the total weight of the stainless steel slag;
The reducing agent is one or more of solar-grade polycrystalline silicon cutting waste and crystalline silicon cutting waste slurry, wherein the content of Si in the solar-grade polycrystalline silicon cutting waste is 90-99wt.%; in the crystalline silicon cutting waste slurry, the Si content is 40-50wt.%;
The usage amount of the reducing agent is as follows: the mass of Si in the reducing agent is 1.0-2.0 times of the theoretical value of Si required when chromium oxide in the stainless steel slag is subjected to the silicothermic reduction reaction of 2Cr 2O3+3Si＝4Cr+3SiO2
(2) Carrying out heat treatment on the slag obtained in the step (1); the conditions of the heat treatment are as follows: preserving heat for 1-2h at 1450 ℃;
(3) Cooling the slag after heat treatment along with a furnace, crushing, screening, and carrying out reselection separation to obtain alloy and tailings; the obtained alloy is micro-carbon chromium alloy, the micro-carbon chromium alloy is returned to steelmaking to be used as an alloy element additive, and tailings are returned to the stainless steel enterprise for internal recycling.
2. The method for efficiently extracting, separating and recovering chromium from stainless steel slag according to claim 1, wherein in the step (1), the stainless steel slag is stainless steel electric arc furnace EAF slag or stainless steel argon oxygen furnace AOD slag with higher Cr content.
3. The method for efficiently extracting, separating and recovering chromium from stainless steel slag according to claim 1, wherein in the step (3), the content of Cr 2O3 in the obtained tailings is less than 1%.
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