AU2021102982A4 - Method for treating cr-containing pickling sludge in slag bath - Google Patents
Method for treating cr-containing pickling sludge in slag bath Download PDFInfo
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- AU2021102982A4 AU2021102982A4 AU2021102982A AU2021102982A AU2021102982A4 AU 2021102982 A4 AU2021102982 A4 AU 2021102982A4 AU 2021102982 A AU2021102982 A AU 2021102982A AU 2021102982 A AU2021102982 A AU 2021102982A AU 2021102982 A4 AU2021102982 A4 AU 2021102982A4
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- slag
- sludge
- temperature
- containing pickling
- pickling sludge
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- 239000002893 slag Substances 0.000 title claims abstract description 91
- 239000010802 sludge Substances 0.000 title claims abstract description 78
- 238000005554 pickling Methods 0.000 title claims abstract description 53
- 238000000034 method Methods 0.000 title claims abstract description 27
- 239000008188 pellet Substances 0.000 claims abstract description 24
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims abstract description 17
- 235000011941 Tilia x europaea Nutrition 0.000 claims abstract description 17
- 239000004571 lime Substances 0.000 claims abstract description 17
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 16
- 239000002923 metal particle Substances 0.000 claims abstract description 13
- 239000000203 mixture Substances 0.000 claims abstract description 10
- 238000001035 drying Methods 0.000 claims abstract description 9
- 238000007885 magnetic separation Methods 0.000 claims abstract description 9
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 8
- 238000012216 screening Methods 0.000 claims abstract description 8
- 238000006243 chemical reaction Methods 0.000 claims abstract description 7
- 229910052751 metal Inorganic materials 0.000 claims abstract description 7
- 239000002184 metal Substances 0.000 claims abstract description 5
- 238000002156 mixing Methods 0.000 claims abstract description 3
- 238000005453 pelletization Methods 0.000 claims abstract description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 4
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 claims description 4
- 229910001220 stainless steel Inorganic materials 0.000 claims description 4
- 239000010935 stainless steel Substances 0.000 claims description 4
- 239000002699 waste material Substances 0.000 claims description 3
- 229910011255 B2O3 Inorganic materials 0.000 claims description 2
- VVTSZOCINPYFDP-UHFFFAOYSA-N [O].[Ar] Chemical compound [O].[Ar] VVTSZOCINPYFDP-UHFFFAOYSA-N 0.000 claims description 2
- 229910052681 coesite Inorganic materials 0.000 claims description 2
- 229910052906 cristobalite Inorganic materials 0.000 claims description 2
- JKWMSGQKBLHBQQ-UHFFFAOYSA-N diboron trioxide Chemical compound O=BOB=O JKWMSGQKBLHBQQ-UHFFFAOYSA-N 0.000 claims description 2
- 238000010891 electric arc Methods 0.000 claims description 2
- 239000007788 liquid Substances 0.000 claims description 2
- 238000006386 neutralization reaction Methods 0.000 claims description 2
- 239000000377 silicon dioxide Substances 0.000 claims description 2
- 235000012239 silicon dioxide Nutrition 0.000 claims description 2
- 229910052682 stishovite Inorganic materials 0.000 claims description 2
- 229910052905 tridymite Inorganic materials 0.000 claims description 2
- 238000005406 washing Methods 0.000 claims description 2
- 229910052925 anhydrite Inorganic materials 0.000 claims 1
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 claims 1
- 238000010438 heat treatment Methods 0.000 claims 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 abstract description 8
- 229910052717 sulfur Inorganic materials 0.000 abstract description 8
- 239000011593 sulfur Substances 0.000 abstract description 8
- 229910052804 chromium Inorganic materials 0.000 abstract description 7
- 230000008569 process Effects 0.000 abstract description 5
- 230000009467 reduction Effects 0.000 abstract description 5
- 229910052742 iron Inorganic materials 0.000 abstract description 4
- 238000009628 steelmaking Methods 0.000 abstract description 3
- 238000004064 recycling Methods 0.000 abstract description 2
- 239000011651 chromium Substances 0.000 description 36
- 239000007789 gas Substances 0.000 description 11
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 7
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 5
- 229910001385 heavy metal Inorganic materials 0.000 description 5
- 238000006722 reduction reaction Methods 0.000 description 5
- 239000002351 wastewater Substances 0.000 description 5
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 4
- 239000002910 solid waste Substances 0.000 description 4
- 229910000519 Ferrosilicon Inorganic materials 0.000 description 3
- 238000001819 mass spectrum Methods 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 239000002920 hazardous waste Substances 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- 238000001878 scanning electron micrograph Methods 0.000 description 2
- 239000002253 acid Substances 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000001784 detoxification Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000002241 glass-ceramic Substances 0.000 description 1
- 231100001261 hazardous Toxicity 0.000 description 1
- 238000010169 landfilling Methods 0.000 description 1
- 238000002386 leaching Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910001719 melilite Inorganic materials 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000009991 scouring Methods 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F11/00—Treatment of sludge; Devices therefor
- C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
- C02F11/14—Treatment of sludge; Devices therefor by de-watering, drying or thickening with addition of chemical agents
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F11/00—Treatment of sludge; Devices therefor
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B5/00—Treatment of metallurgical slag ; Artificial stone from molten metallurgical slag
- C04B5/06—Ingredients, other than water, added to the molten slag or to the granulating medium or before remelting; Treatment with gases or gas generating compounds, e.g. to obtain porous slag
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F11/00—Treatment of sludge; Devices therefor
- C02F11/008—Sludge treatment by fixation or solidification
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/20—Heavy metals or heavy metal compounds
- C02F2101/22—Chromium or chromium compounds, e.g. chromates
-
- 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
-
- 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
Abstract
OF THE DISCLOSURE
The present disclosure provides a method for treating Cr-containing pickling sludge in a slag
bath, including the following steps: 1, adding a reducing agent, lime and a fluxing agent to the
Cr-containing pickling sludge and fully mixing; 2, pelletizing the mixture by using a pelletizer and
drying at a certain temperature; 3, putting the dried sludge pellets from step (2) into the
high-temperature metallurgical slag for a slag bath reaction; and 4, subjecting cooled slag to
crushing, screening and magnetic separation, thus separating out metal particles. Under the
conditions of this method, the Cr-containing pickling sludge is thoroughly reduced and detoxified
by using the high-temperature metallurgical slag so that most of sulfur in the sludge is immobilized
in the slag phase. No secondary pollution is caused during the process and valuable metal elements
such as Cr and Fe in the high-temperature slag and the sludge can be fully reduced to the metal
phase and then recovered by magnetic separation. The treatment method provided in the present
disclosure is simple to operate and can be implemented during a steelmaking process without
secondary emission. Thus, online recycling and emission reduction at source of the Cr-containing
pickling sludge are actually realized.
Description
[01] The present disclosure relates to the technical field of metallurgical engineering, and in particular, to a method for treating chromium (Cr)-containing pickling sludge in a slag bath.
[02] Pickling sludge, also known as sludge from the treatment of pickling waste water, is a solid waste generated from the treatment of pickling waste water discharged during a metal surface treatment process. At present, centralized treatment of the pickling waste water can hardly be realized. Most of the pickling waste water are treated by the enterprise which generates the pickling waste water using a cheap and easy lime neutralization-precipitation method. Due to poor precipitation effect of the lime on heavy metals, a large amount of lime would be enveloped by other flocs and sink into the sludge before reacting during reaction, thus resulting in a large amount of sludge. Moreover, the pickling sludge may contain a large amount of heavy metals (e.g., nickel, chromium and iron) and reacted acids that are not precipitated and removed effectively. Thus, if the pickling sludge is dumped arbitrarily or landfilled simply, a severe environmental pollution problem will be caused. The current treatment methods of the pickling sludge in China mainly include stacking and simple landfilling. Such treatment methods would cause severe pollution to the environment and heavy metals left in the sludge would cause waste of resources.
[03] In 2018, the pickling sludge from the production of stainless steel was explicitly put into the list of hazardous solid wastes by China and not allowed to leave factories. In China, the annual output of stainless steel is approximately 40 million tons and about one million ton of Cr-containing pickling sludge needs to be disposed in each year. Therefore, it is imperative to realize on-line treatment of the Cr-containing pickling sludge and achieve emission reduction at source. In related treatment techniques, wet treatment and material production from solid wastes are basically infeasible under the current policies. Moreover, because of multi-stage recovery of heavy metal elements and SO42- from sludge, the wet treatment is complex in process and high in cost and thus not recommended. When the Cr-containing pickling sludge is used as the raw material to produce ceramics, glass ceramics, etc., there may be potential safety hazards due to excessively low addition amount and limited consumption amount of the sludge, and difficultly accurate control of Cr leaching behavior under current conditions.
[04] An objective of the present disclosure is to provide a method for treating Cr-containing pickling sludge in a slag bath to solve the problems of secondary pollution caused by sulfur in the Cr-containing pickling sludge and difficult recovery of heavy metal chromium.
[05] To solve the mentioned technical problems, the present disclosure adopts the following technical solution.
[06] A method for treating chromium (Cr)-containing pickling sludge in a slag bath includes the following steps:
[07] (1) adding a reducing agent, lime and a fluxing agent to the Cr-containing pickling sludge and fully mixing;
[08] (2) pelletizing the mixture by using a pelletizer and drying at a certain temperature, thereby obtaining Cr-containing pickling sludge pellets for treatment in a slag bath;
[09] (3) putting the dried sludge pellets from step (2) into high-temperature metallurgical slag for a slag bath reaction; and
[10] (4) subjecting cooled slag to crushing, screening and magnetic separation, thus separating out metal particles.
[11] Preferably, the pickling sludge may include sludge generated from lime neutralization and drying of a waste liquid from product washing using sulfuric acid during the production of a stainless steel enterprise.
[12] Further preferably, the sludge may include the following components: 25% to 35% of Fe203, 3% to 5% of SiO2, 55% to 65% of CaSO 4 , and 2% to 6% of Cr203.
[13] Further preferably, the reducing agent used in step (1) may be a carbonaceous reducing agent.
[14] Further preferably, the fluxing agent used in step (1) may be boric oxide.
[15] Further preferably, a mass ratio of the reducing agent, the lime, the sludge and the fluxing agent in step (1) may be (16% to 2 2 %):( 7 % to 9%):( 7 1% to 7 6 %):(1% to 3%).
[16] Further preferably, the drying in step (2) may be conducted at a temperature ranging from 780 to 800°C for 50 to 60 minutes.
[17] Further preferably, the metallurgical slag in step (3) may be one or more from the group consisting of argon oxygen decarburisation (AOD) slag, electric arc furnace (EAF) slag and converter slag.
[18] Further preferably, the carbonaceous reducing agent and ferrosilicon powder may be injected into the slag before the carbon-containing pickling sludge pellets are put into the slag in step (3), where a mass ratio of the slag, the carbonaceous reducing agent and the ferrosilicon powder may be 99%:(0.8% to 0.9%):(0.1% to 0.2%).
[19] Further preferably, a mass ratio of the sludge pellets to the high-temperature metallurgical slag in step (3) may be 3% to 10%.
[20] Further preferably, the treatment in the slag bath in step (3) may be conducted at a temperature not below 1550°C for 10 to 20 minutes.
[21] Compared with the prior art, the present disclosure has the following advantages: the present disclosure develops a technique for treating Cr-containing pickling sludge in a slag bath, which is intended to treat Cr-containing pickling sludge type hazardous wastes in a slag bath of solid wastes generated from another unit of a long process. Thorough reduction and detoxification of the Cr-containing pickling sludge are achieved so that most of sulfur in the sludge is immobilized in the slag phase. No secondary pollution is caused during the process and valuable metal elements in the slag and the sludge can be reduced, separated and recovered simultaneously. Moreover, high-temperature sensible heat of the metallurgical slag is fully utilized and the utilization of both energy and mass is achieved. As a result, emission reduction at source of Cr-containing pickling sludge type hazardous wastes is realized. The treatment method provided in the present disclosure is simple to operate and can be implemented during a steelmaking process without secondary emission. Thus, online recycling and emission reduction at source of the Cr-containing pickling sludge are actually realized.
[22] FIG. 1 is a flowchart of a method for treating Cr-containing pickling sludge pellets in a slag bath according to an example of the present disclosure.
[23] FIG. 2 is a technical roadmap of a method for treating Cr-containing pickling sludge pellets in a slag bath according to an example of the present disclosure.
[24] FIG. 3 shows images of slag and metal particles obtained from the treatment of Cr-containing pickling sludge pellets in a slag bath according to example 2 of the present disclosure.
[25] FIG. 4 is a mass spectrum of components of a gas released from the treatment of Cr-containing pickling sludge in a slag bath according to example 2 of the present disclosure.
[26] FIG. 5 is a mass spectrum of S02 gas released from the treatment of Cr-containing pickling sludge in a slag bath according to example 2 of the present disclosure.
[27] Description of reference numerals: 1, sludge pellets; 2, high-temperature drying furnace; 3, metallurgical slag; 4, slag ladle; 5, crushing/screening/magnetic separation apparatus; 6-1, slag; 6-2, SEM image of slag; 7, metal particles; 8, gas generated over 0 to 10 minutes; 8-1, S02 gas over 0 to minutes; 9, air; 9-1, S02 gas in air; 10, gas generated over 10 to 15 minutes; and 10-1, S02 gas over 10 to 15 minutes.
[28] The following describes the preferred embodiment of the present disclosure in more detail to make the advantages and features of the present disclosure more readily understood by those skilled in the art and further to define the protection scope of the present disclosure.
[29] The operation of the treatment method provided in the present disclosure is as shown in FIG. 2, where during the slag dumping after the steelmaking process (converter or AOD furnace, etc.) is ended, the sludge pellets 1 prepared according to requirements are put into a slag ladle 4 together with slag 3 after being subjected to drying 2. Under the favorable dynamic condition created by scouring of the high-temperature slag, a carbonaceous reducing agent, lime, etc. in the sludge pellets undergo a self-reduction reaction with the Cr-containing pickling sludge first, and the pellets are then dissolved in the slag. Excessive C may in turn reduce metal oxides in the slag. All the metals generated may be integrated. Besides, such elements as sulfur may enter the slag phase and exist stably. Cooled slag may be subjected to crushing/screening/magnetic separation by using a crusher 5 so that the slag 6 and the metal particles 7 are separated out.
[30] Example 1:
[31] (1) A reducing agent graphite powder and lime were added to Cr-containing pickling sludge and fully mixed, where a mass ratio of the graphite powder, the lime and the pickling sludge was 22%:7%:71%.
[32] (2) The mixture was pelletized by using a pelletizer and dried at 800°C for 50 minutes into Cr-containing pickling sludge pellets for treatment in a slag bath.
[33] (3) AOD slag was fully mixed with a carbonaceous reducing agent and ferrosilicon powder in a mass ratio of 9 8 .9 %:0. 8 5 %:0. 2 5 %. The mixture was heated at 1550°C to melt and this temperature was kept constant for 20 minutes. The dried sludge pellets from step (2) were put into the AOD slag for a slag bath reaction at 1550°C for 15 minutes, where a mass ratio of the sludge pellets to the AOD slag was 3%.
[34] (4) Cooled slag was subjected to crushing, screening and magnetic separation so that metal particles were separated out.
[35] Example 2
[36] (1) A reducing agent graphite powder, a fluxing agent and lime were added to Cr-containing pickling sludge and fully mixed, where a mass ratio of the graphite powder, the lime and the pickling sludge was 18%:7%:72%.
[37] (2) The mixture was pelletized by using a pelletizer and dried at 780°C for 60 minutes into Cr-containing pickling sludge pellets for treatment in a slag bath.
[38] (3) AOD slag was heated at 1550°C to melt and this temperature was kept constant for 20 minutes. The dried sludge pellets from step (2) were put into the AOD slag for a slag bath reaction at 1550°C for 20 minutes, where a mass ratio of the sludge pellets to the AOD slag was 5%.
[39] (4) Cooled slag was subjected to crushing, screening and magnetic separation so that metal particles were separated out. FIG. 3 illustrates the slag and the metal particles separated out.
[40] Example 3
[41] (1) A reducing agent graphite powder and lime were added to Cr-containing pickling sludge and fully mixed, where a mass ratio of the graphite powder, the lime and the pickling sludge was 16%:7%:7 7 %.
[42] (2) The mixture was pelletized by using a pelletizer and dried at 800°C for 50 minutes into Cr-containing pickling sludge pellets for treatment in a slag bath.
[43] (3) Converter slag was heated at 1600°C to melt and this temperature was kept constant for minutes. The dried sludge pellets from step (2) were put into the converter slag for a slag bath reaction at 1600°C for 15 minutes, where a mass ratio of the sludge pellets to the converter slag was %.
[44] (4) Cooled slag was subjected to crushing, screening and magnetic separation so that metal particles were separated out.
[45] Example 4
[46] Slag samples from example 1 and example 2 were crushed, respectively. After metal particles were absorbed by using a magnet, the slag samples were measured on S content and SEM images thereof were observed, and metal samples were measured on Fe/Cr content. Results shown that as shown by SEM microstructures of the slag samples, sulfur were mainly present stably in the form of dendritic CaS crystals, and a large amount of melilite were generated in the slag. In example 1, more than 94% of sulfur was present stably in the slag phase, while more than 95% of valuable elements such as Fe and Cr were recovered in the form of metal particles. In example 2, more than 99% of sulfur was present stably in the slag phase, while more than 90% of valuable elements such as Fe and Cr were recovered in the form of metal particles. A gas released during the treatment of the Cr-containing pickling sludge in the slag bath in example 2 was collected and the components of the gas were analyzed. FIG. 4 shows the mass spectrum of the components of the released gas. As can be seen from the figure, the released gas is a mixture of Ar, CO/N 2 , C02 and S02.
[47] As can be seen from FIG. 5, most of released S02 was from air and a small part of S02 was released during the treatment of the Cr-containing pickling sludge in the slag bath. It was shown that the sulfur element was fully immobilized in the slag phase.
[48] The examples described above are only intended to describe the preferred examples of the present disclosure, and are not intended to limit the scope of the present disclosure. Various modifications and improvements performed on the technical solution of the present disclosure by those of ordinary skill in the art without departing from the design spirit of the present disclosure should fall within the protection scope as defined by the claims of the present disclosure.
Claims (5)
1. A method for treating Cr-containing pickling sludge in a slag bath, comprising the following steps: (1) adding a reducing agent, lime and a fluxing agent to the Cr-containing pickling sludge, and fully mixing, to obtain a mixture; (2) pelletizing the mixture by using a pelletizer and drying, thereby obtaining Cr-containing pickling sludge pellets for treatment in a slag bath; (3) heating high-temperature metallurgical slag to melt, putting the dried sludge pellets from step (2) into the high-temperature metallurgical slag for a slag bath reaction; and (4) subjecting cooled slag to crushing, screening and magnetic separation, thus separating out metal particles.
2. The treatment method according to claim 1, wherein the pickling sludge comprises sludge generated from lime neutralization and drying of a waste liquid from product washing using sulfuric acid during the production of a stainless steel enterprise.
3. The treatment method according to claim 2, wherein the sludge comprises the following components: 25% to 35% of Fe203, 3% to 5% of SiO2 , 55% to 65% of CaSO4 , and 2% to 6% of Cr203.
4. The treatment method according to claim 1, wherein the reducing agent used in step (1) is a carbonaceous reducing agent; wherein the fluxing agent used in step (1) is boric oxide; wherein a mass ratio of the reducing agent, the lime, the sludge and the fluxing agent in step (1) is (16% to 20%):(7% to 9%):(72% to 76%):(1% to 3%); wherein the drying in step (2) is conducted at a temperature ranging from 780 to 800°C for 50 to 60 minutes.
5. The treatment method according to claim 1, wherein the metallurgical slag in step (3) is one or more from the group consisting of argon oxygen decarburisation (AOD) slag, electric arc furnace (EAF) slag and converter slag; wherein a mass ratio of the sludge pellets to the high-temperature metallurgical slag in step (3) is 3% to 10%; wherein the treatment in the slag bath in step (3) is conducted at a temperature not below
1550°C for 10to 20 minutes.
－1/3－ 31 May 2021
Mix
Pelletize 2021102982
Dry
High-temperature slag bath
Slag dump and cool
Crush, screen and magnetically separate
Metal and slag
FIG. 1
－2/3－
FIG. 3 FIG. 2
－3/3－
FIG. 5 FIG. 4
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AU2021102982A AU2021102982A4 (en) | 2021-05-31 | 2021-05-31 | Method for treating cr-containing pickling sludge in slag bath |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AU2021102982A AU2021102982A4 (en) | 2021-05-31 | 2021-05-31 | Method for treating cr-containing pickling sludge in slag bath |
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| Publication Number | Publication Date |
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| AU2021102982A4 true AU2021102982A4 (en) | 2021-08-26 |
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| AU2021102982A Active AU2021102982A4 (en) | 2021-05-31 | 2021-05-31 | Method for treating cr-containing pickling sludge in slag bath |
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2021
- 2021-05-31 AU AU2021102982A patent/AU2021102982A4/en active Active
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