CN113151672A - Method for improving compression strength of alkaline pellets prepared with limestone - Google Patents
Method for improving compression strength of alkaline pellets prepared with limestone Download PDFInfo
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- CN113151672A CN113151672A CN202110442481.1A CN202110442481A CN113151672A CN 113151672 A CN113151672 A CN 113151672A CN 202110442481 A CN202110442481 A CN 202110442481A CN 113151672 A CN113151672 A CN 113151672A
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- 239000008188 pellet Substances 0.000 title claims abstract description 60
- 238000000034 method Methods 0.000 title claims abstract description 57
- 235000019738 Limestone Nutrition 0.000 title claims abstract description 45
- 239000006028 limestone Substances 0.000 title claims abstract description 45
- 230000006835 compression Effects 0.000 title description 6
- 238000007906 compression Methods 0.000 title description 6
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 68
- 239000000440 bentonite Substances 0.000 claims abstract description 68
- 229910000278 bentonite Inorganic materials 0.000 claims abstract description 68
- SVPXDRXYRYOSEX-UHFFFAOYSA-N bentoquatam Chemical compound O.O=[Si]=O.O=[Al]O[Al]=O SVPXDRXYRYOSEX-UHFFFAOYSA-N 0.000 claims abstract description 68
- 239000000463 material Substances 0.000 claims abstract description 53
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 36
- 239000001301 oxygen Substances 0.000 claims abstract description 36
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 36
- 230000008569 process Effects 0.000 claims abstract description 36
- 229910052742 iron Inorganic materials 0.000 claims abstract description 34
- 239000000395 magnesium oxide Substances 0.000 claims abstract description 25
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims abstract description 25
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 claims abstract description 25
- 239000000843 powder Substances 0.000 claims abstract description 17
- 238000005453 pelletization Methods 0.000 claims abstract description 11
- 229910052500 inorganic mineral Inorganic materials 0.000 claims abstract description 9
- 239000011707 mineral Substances 0.000 claims abstract description 9
- 238000012216 screening Methods 0.000 claims abstract description 9
- 238000003756 stirring Methods 0.000 claims description 44
- 238000001816 cooling Methods 0.000 claims description 34
- 238000006243 chemical reaction Methods 0.000 claims description 31
- 238000000227 grinding Methods 0.000 claims description 31
- 239000011259 mixed solution Substances 0.000 claims description 31
- 238000002156 mixing Methods 0.000 claims description 29
- PAYRUJLWNCNPSJ-UHFFFAOYSA-N Aniline Chemical compound NC1=CC=CC=C1 PAYRUJLWNCNPSJ-UHFFFAOYSA-N 0.000 claims description 28
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 28
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 24
- 239000002245 particle Substances 0.000 claims description 23
- 238000005406 washing Methods 0.000 claims description 23
- 239000007864 aqueous solution Substances 0.000 claims description 21
- 238000001035 drying Methods 0.000 claims description 21
- ROOXNKNUYICQNP-UHFFFAOYSA-N ammonium persulfate Chemical compound [NH4+].[NH4+].[O-]S(=O)(=O)OOS([O-])(=O)=O ROOXNKNUYICQNP-UHFFFAOYSA-N 0.000 claims description 20
- 239000008367 deionised water Substances 0.000 claims description 18
- 229910021641 deionized water Inorganic materials 0.000 claims description 18
- 239000000243 solution Substances 0.000 claims description 17
- WYTZZXDRDKSJID-UHFFFAOYSA-N (3-aminopropyl)triethoxysilane Chemical compound CCO[Si](OCC)(OCC)CCCN WYTZZXDRDKSJID-UHFFFAOYSA-N 0.000 claims description 16
- 239000002243 precursor Substances 0.000 claims description 16
- 239000011882 ultra-fine particle Substances 0.000 claims description 16
- 238000007873 sieving Methods 0.000 claims description 15
- 238000001914 filtration Methods 0.000 claims description 13
- 239000001509 sodium citrate Substances 0.000 claims description 12
- NLJMYIDDQXHKNR-UHFFFAOYSA-K sodium citrate Chemical compound O.O.[Na+].[Na+].[Na+].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O NLJMYIDDQXHKNR-UHFFFAOYSA-K 0.000 claims description 12
- 238000010438 heat treatment Methods 0.000 claims description 11
- 229910001870 ammonium persulfate Inorganic materials 0.000 claims description 10
- 238000000967 suction filtration Methods 0.000 claims description 10
- 238000001291 vacuum drying Methods 0.000 claims description 10
- CSNNHWWHGAXBCP-UHFFFAOYSA-L Magnesium sulfate Chemical compound [Mg+2].[O-][S+2]([O-])([O-])[O-] CSNNHWWHGAXBCP-UHFFFAOYSA-L 0.000 claims description 8
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims description 8
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 claims description 8
- 239000000292 calcium oxide Substances 0.000 claims description 8
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims description 8
- 239000004202 carbamide Substances 0.000 claims description 8
- 235000010755 mineral Nutrition 0.000 claims description 8
- 229920001495 poly(sodium acrylate) polymer Polymers 0.000 claims description 8
- 238000002791 soaking Methods 0.000 claims description 8
- NNMHYFLPFNGQFZ-UHFFFAOYSA-M sodium polyacrylate Chemical compound [Na+].[O-]C(=O)C=C NNMHYFLPFNGQFZ-UHFFFAOYSA-M 0.000 claims description 8
- 238000007792 addition Methods 0.000 claims description 6
- 239000000853 adhesive Substances 0.000 claims description 6
- 230000001070 adhesive effect Effects 0.000 claims description 6
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 5
- 239000006185 dispersion Substances 0.000 claims description 5
- 230000007935 neutral effect Effects 0.000 claims description 5
- 238000010992 reflux Methods 0.000 claims description 5
- 230000003647 oxidation Effects 0.000 abstract description 7
- 238000007254 oxidation reaction Methods 0.000 abstract description 7
- 239000008187 granular material Substances 0.000 abstract description 2
- 239000007791 liquid phase Substances 0.000 abstract description 2
- 238000001354 calcination Methods 0.000 abstract 1
- 230000000052 comparative effect Effects 0.000 description 8
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 6
- 239000011229 interlayer Substances 0.000 description 6
- 229920000767 polyaniline Polymers 0.000 description 6
- 229920000642 polymer Polymers 0.000 description 6
- 125000002924 primary amino group Chemical group [H]N([H])* 0.000 description 5
- 239000002994 raw material Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 239000011148 porous material Substances 0.000 description 3
- 238000001179 sorption measurement Methods 0.000 description 3
- 239000006087 Silane Coupling Agent Substances 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- IDGUHHHQCWSQLU-UHFFFAOYSA-N ethanol;hydrate Chemical compound O.CCO IDGUHHHQCWSQLU-UHFFFAOYSA-N 0.000 description 2
- 239000010410 layer Substances 0.000 description 2
- 239000003607 modifier Substances 0.000 description 2
- 238000006116 polymerization reaction Methods 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 125000003277 amino group Chemical group 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 229910052681 coesite Inorganic materials 0.000 description 1
- 229910052593 corundum Inorganic materials 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 229910052682 stishovite Inorganic materials 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 229910052905 tridymite Inorganic materials 0.000 description 1
- 229910001845 yogo sapphire Inorganic materials 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
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/14—Agglomerating; Briquetting; Binding; Granulating
- C22B1/24—Binding; Briquetting ; Granulating
- C22B1/2406—Binding; Briquetting ; Granulating pelletizing
-
- 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
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/14—Agglomerating; Briquetting; Binding; Granulating
- C22B1/24—Binding; Briquetting ; Granulating
- C22B1/242—Binding; Briquetting ; Granulating with binders
- C22B1/243—Binding; Briquetting ; Granulating with binders inorganic
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Geochemistry & Mineralogy (AREA)
- Geology (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Manufacture And Refinement Of Metals (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
Abstract
The invention discloses a method for improving the compressive strength of alkaline pellets prepared with limestone, which comprises the following steps of preparing treated magnesium oxide; secondly, preparing mixed mineral powder; thirdly, preparing a roasting material, pelletizing the roasting material, screening and roasting the manufactured green pellets, and controlling the using amount of the bonding bentonite to be 1-2.5% of the weight of the roasting material; through carrying out preliminary treatment to magnesium oxide, make magnesium oxide self have higher porosity, make inside oxygen can get into the pelletizing through the hole in the oxygen boosting process, increase the oxidation of iron ore granule, improve the compressive strength of pellet, solved and improved the calcination temperature and can improve the alkaline pellet compressive strength who joins in marriage the lime stone in certain extent, but too high temperature not only increases the energy resource consumption, and produces too much liquid phase, influence the technical problem of pellet compressive strength on the contrary.
Description
Technical Field
The invention belongs to the technical field of blast furnace ironmaking, and particularly relates to a method for improving the compressive strength of alkaline pellets prepared with limestone.
Background
Pellet ore is one of main raw materials for blast furnace ironmaking, and common acid pellet ore is mainly produced in the current market. The acid pellets are naturally alkaline pellets, SiO2And Al2O3The content of the elements is relatively high, and the content of alkaline matters such as calcium, magnesium and the like is low, so that the blast furnace can only be matched with high-alkalinity sinter ore for use. The pellet with the binary alkalinity of more than 0.6 percent is called alkaline pellet. The alkaline pellet has the advantages of high reducibility, good molten drop performance and the like, but the compressive strength of the alkaline pellet is difficult to improve, and particularly, the compressive strength of the alkaline pellet is obviously reduced along with the improvement of alkalinity. The main reason is that the basic additives such as limestone and the like are decomposed and absorb heat in the roasting process, and the basic particles are coarse to disperse iron ore particles, so that the oxidation and recrystallization of the iron ore particles are weakened. Although the roasting temperature is increased to a certain rangeThe compression strength of the alkaline pellet ore with limestone can be improved in the enclosure, but the excessive temperature not only increases the energy consumption, but also generates excessive liquid phase, and influences the compression strength of the pellet ore.
Disclosure of Invention
In order to overcome the technical problems, the invention provides a method for improving the compressive strength of alkaline pellets prepared with limestone.
The purpose of the invention can be realized by the following technical scheme:
a method for improving the compressive strength of an alkaline pellet ore prepared with limestone comprises the following steps:
adding 2.5-3.0 parts by weight of anhydrous magnesium sulfate and 17.12-17.56 parts by weight of urea into deionized water, uniformly stirring, adding 0.2-0.5 part by weight of sodium polyacrylate, magnetically stirring for 1h to prepare a mixed solution, transferring the mixed solution into a reaction kettle, uniformly stirring at a constant speed at 180 ℃ for 6h, cooling to room temperature after the reaction is finished, filtering, washing and drying to prepare a precursor, then placing the precursor into a muffle furnace, roasting at 550 ℃ for 5h, and cooling to prepare treated magnesium oxide;
step two, uniformly mixing 0.5 to 2.0 weight parts of treated magnesium oxide, 2.3 to 3.5 weight parts of calcium oxide and 55 to 70 weight parts of fine iron ore, crushing and grinding until the particle size is 1 to 5mm, and preparing mixed ore powder;
grinding limestone until the particle size is less than 3 mu m to prepare ultrafine particle limestone, mixing the ultrafine particle limestone with mixed mineral powder, adding bonded bentonite, uniformly mixing to prepare a roasting material, pelletizing the roasting material, screening to obtain green pellets, and roasting, wherein the dosage of the bonded bentonite is controlled to be 1-2.5% of the weight of the roasting material.
Further, the roasting in the third step comprises drying, preheating, roasting, soaking and cooling; oxygen enrichment is carried out in the preheating and roasting processes, the oxygen content in the preheating process is kept between 15 and 18 percent, and the oxygen content in the roasting process is kept between 12 and 16 percent.
Further, the iron content of the refined iron ore is more than 75%.
Further, the binding bentonite comprises the following steps:
step S1, placing bentonite into a sulfuric acid solution with the concentration of 1mol/L, heating in a water bath at 45-60 ℃, stirring for 12 hours, filtering, washing with deionized water to be neutral, then drying in vacuum for 10 hours, grinding, and sieving with a 100-mesh sieve to obtain a sample for later use;
step S2, adding the prepared sample into the mixed solution, stirring at a constant speed for 10min, adding 3-aminopropyltriethoxysilane, heating to 65-80 ℃, carrying out reflux reaction for 12h, cooling to room temperature after the reaction is finished, carrying out suction filtration, washing for three times, carrying out vacuum drying for 10h, grinding, and sieving with a 200-mesh sieve to obtain a primary material;
step S3, adding aniline into a sodium citrate aqueous solution with the mass fraction of 20%, adding a primary material after uniform dispersion, continuously dispersing for 10min, cooling to 0-10 ℃, dropwise adding an ammonium persulfate aqueous solution with the mass fraction of 10% while stirring, controlling the dropwise adding time to be 30min, stirring after complete dropwise addition, reacting for 10h, performing suction filtration after the reaction is finished, washing for three times, performing vacuum drying for 10h, grinding, and sieving with a 200-mesh sieve to obtain the adhesive bentonite.
Step S1, placing bentonite in sulfuric acid solution, acidifying the bentonite by sulfuric acid to obtain a sample, wherein the sample is acidified bentonite, then step S2, dispersing the acidified bentonite in ethanol water solution, adding 3-aminopropyl triethoxysilane as a modifier, 3-aminopropyl triethoxysilane as a silane coupling agent, modifying the acidified bentonite by 3-aminopropyl triethoxysilane to introduce amino on the surface of the bentonite to obtain a primary material, wherein the amino is introduced on the primary material, and polyaniline has the characteristic of easy doping in the synthesis process, so that aniline is added into sodium citrate water solution to be dispersed in step S3 to enable the finally prepared polyaniline to have positive charges, then the primary material is added, the polyaniline doped with citric acid is grafted on the surface of the primary material bentonite, and the amino participates in the polymerization reaction of the aniline on the surface of the bentonite, the polymer is grafted on the surface of the bentonite, so that the interlayer spacing of the bentonite is enlarged, the specific surface area of the bentonite is increased, adsorption sites are increased, the polymer is decomposed by heating in the roasting process, the adhesion effect of the adhered bentonite and other raw materials is further increased, the roasting is facilitated, the uniform stability of the alkaline pellets obtained by roasting is improved, the compressive strength of the alkaline pellets is further improved, and the larger interlayer spacing of the alkaline pellets can enable oxygen to enter the interior of the pellets through pores in the oxygen enrichment process, so that the oxidation of iron ore particles is increased, and the compressive strength of the pellets is further improved.
Further, the mixed solution is formed by mixing absolute ethyl alcohol and deionized water according to the volume ratio of 70: 30.
Further, the dosage ratio of the bentonite solution to the sulfuric acid solution in the step S1 is 5-10 g: 200-250mL, the dosage ratio of the sample, the mixed solution and the 3-aminopropyltriethoxysilane in the step S2 is 5 g: 150 mL: 5g, and the dosage ratio of the aniline, the sodium citrate aqueous solution, the primary material and the ammonium persulfate aqueous solution in the step S3 is 3-5 g: 200-250 mL: 3-5 g: 8-10 mL.
The invention has the beneficial effects that:
the invention relates to a method for improving the compression strength of alkaline pellets prepared with limestone, which comprises the steps of preliminarily treating magnesium oxide to ensure that the magnesium oxide has higher porosity, enabling oxygen to enter the pellets through pores in the oxygen enrichment process, increasing the oxidation of iron ore particles and improving the compression strength of the pellets, preparing adhesive bentonite, placing bentonite in sulfuric acid solution in step S1 in the preparation process, acidifying the bentonite through sulfuric acid to prepare a sample, wherein the sample is acidified bentonite, dispersing the acidified bentonite in ethanol water solution in step S2, adding 3-aminopropyltriethoxysilane as a modifier, 3-aminopropyltriethoxysilane as a silane coupling agent, introducing amino groups into the surface of the bentonite after the bentonite is modified and acidified through the 3-aminopropyltriethoxysilane, preparing a primary material, introducing amino into the primary material, wherein the polyaniline has the characteristic of easy doping in the synthesis process, so that aniline is added into a sodium citrate aqueous solution to be dispersed in step S3, so that the finally prepared polyaniline has positive charges, then the primary material is added, the polyaniline doped with citric acid is grafted on the surface of the primary material bentonite, the amino participates in the polymerization reaction of the aniline on the surface of the bentonite to play a coupling role, a layer of polymer is grafted on the surface of the bentonite to enlarge the interlayer spacing of the bentonite, increase the specific surface area of the bentonite and increase the adsorption sites, the polymer is heated and decomposed in the roasting process, the adhesion effect of the adhered bentonite and other raw materials is further increased, the roasting is facilitated, the uniform stability of the roasted alkaline pellets is improved, the compressive strength of the alkaline pellets is improved, and the larger interlayer spacing of the primary material further allows oxygen to enter the pellets through the high interlayer spacing in the oxygen enrichment process, further increasing the oxidation of iron ore particles and further improving the compressive strength of the pellets.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
A method for improving the compressive strength of an alkaline pellet ore prepared with limestone comprises the following steps:
adding 2.5 parts by weight of anhydrous magnesium sulfate and 17.12 parts by weight of urea into deionized water, uniformly stirring, adding 0.2 part by weight of sodium polyacrylate, magnetically stirring for 1h to obtain a mixed solution, transferring the mixed solution into a reaction kettle, uniformly stirring at 150 ℃, reacting for 6h, cooling to room temperature after the reaction is finished, filtering, washing and drying to obtain a precursor, placing the precursor into a muffle furnace, roasting at 500 ℃ for 5h, and cooling to obtain treated magnesium oxide;
step two, uniformly mixing 0.5 part by weight of the treated magnesium oxide, 2.3 parts by weight of calcium oxide and 55 parts by weight of fine iron ore, and crushing and grinding until the particle size is 1mm to prepare mixed ore powder;
grinding limestone until the particle size is less than 3 mu m to prepare ultrafine particle limestone, mixing the ultrafine particle limestone with mixed mineral powder, adding bonded bentonite, uniformly mixing to prepare a roasting material, pelletizing the roasting material, screening to obtain green pellets, and roasting, wherein the dosage of the bonded bentonite is controlled to be 1% of the weight of the roasting material.
The third step of roasting comprises drying, preheating, roasting, soaking and cooling; oxygen enrichment is carried out in the preheating and roasting processes, the oxygen content in the preheating process is kept at 15%, and the oxygen content in the roasting process is kept at 12%.
The iron content of the refined iron ore is more than 75%.
Example 2
A method for improving the compressive strength of an alkaline pellet ore prepared with limestone comprises the following steps:
adding 2.8 parts by weight of anhydrous magnesium sulfate and 17.35 parts by weight of urea into deionized water, uniformly stirring, adding 0.4 part by weight of sodium polyacrylate, magnetically stirring for 1h to obtain a mixed solution, transferring the mixed solution into a reaction kettle, uniformly stirring at 150 ℃, reacting for 6h, cooling to room temperature after the reaction is finished, filtering, washing and drying to obtain a precursor, placing the precursor into a muffle furnace, roasting at 500 ℃ for 5h, and cooling to obtain treated magnesium oxide;
step two, uniformly mixing 1.0 part by weight of the treated magnesium oxide, 3.0 parts by weight of calcium oxide and 60 parts by weight of fine iron ore, and crushing and grinding until the particle size is 3mm to prepare mixed ore powder;
grinding limestone until the particle size is less than 3 mu m to prepare ultrafine particle limestone, mixing the ultrafine particle limestone with mixed mineral powder, adding bonded bentonite, uniformly mixing to prepare a roasting material, pelletizing the roasting material, screening to obtain green pellets, and roasting, wherein the dosage of the bonded bentonite is controlled to be 1.5% of the weight of the roasting material.
The third step of roasting comprises drying, preheating, roasting, soaking and cooling; oxygen enrichment is carried out in the preheating and roasting processes, the oxygen content in the preheating process is kept at 15%, and the oxygen content in the roasting process is kept at 12%.
The iron content of the refined iron ore is more than 75%.
Example 3
A method for improving the compressive strength of an alkaline pellet ore prepared with limestone comprises the following steps:
adding 3.0 parts by weight of anhydrous magnesium sulfate and 17.56 parts by weight of urea into deionized water, uniformly stirring, adding 0.5 part by weight of sodium polyacrylate, magnetically stirring for 1h to obtain a mixed solution, transferring the mixed solution into a reaction kettle, uniformly stirring at 180 ℃, reacting for 6h, cooling to room temperature after the reaction is finished, filtering, washing and drying to obtain a precursor, placing the precursor into a muffle furnace, roasting at 550 ℃ for 5h, and cooling to obtain treated magnesium oxide;
step two, uniformly mixing 2.0 parts by weight of the treated magnesium oxide, 3.5 parts by weight of calcium oxide and 70 parts by weight of fine iron ore, and crushing and grinding until the particle size is 5mm to prepare mixed ore powder;
grinding limestone until the particle size is less than 3 mu m to prepare ultrafine particle limestone, mixing the ultrafine particle limestone with mixed mineral powder, adding bonded bentonite, uniformly mixing to prepare a roasting material, pelletizing the roasting material, screening to obtain green pellets, and roasting, wherein the dosage of the bonded bentonite is controlled to be 2.5% of the weight of the roasting material.
The third step of roasting comprises drying, preheating, roasting, soaking and cooling; oxygen enrichment is carried out during the preheating and roasting processes, the oxygen content during the preheating process is kept at 18 percent, and the oxygen content during the roasting process is kept at 16 percent.
The iron content of the refined iron ore is more than 75%.
Comparative example 1
This comparative example compared to example 1, where magnesium oxide was used instead of treated magnesium oxide.
The compressive strength of the alkaline pellets of examples 1 to 3 and comparative example 1 was measured according to the national standard GB/T14201-93 "method for measuring compressive strength of iron ore pellets", and the results are shown in Table 1 below;
TABLE 1
| Example 1 | Example 2 | Example 3 | Comparative example 1 | |
| Compressive strength N/P | 2858±10 | 2860±8.2 | 2858±7.8 | 2750±710 |
Example 4
A method for improving the compressive strength of an alkaline pellet ore prepared with limestone comprises the following steps:
adding 2.5 parts by weight of anhydrous magnesium sulfate and 17.12 parts by weight of urea into deionized water, uniformly stirring, adding 0.2 part by weight of sodium polyacrylate, magnetically stirring for 1h to obtain a mixed solution, transferring the mixed solution into a reaction kettle, uniformly stirring at 150 ℃, reacting for 6h, cooling to room temperature after the reaction is finished, filtering, washing and drying to obtain a precursor, placing the precursor into a muffle furnace, roasting at 500 ℃ for 5h, and cooling to obtain treated magnesium oxide;
step two, uniformly mixing 0.5 part by weight of the treated magnesium oxide, 2.3 parts by weight of calcium oxide and 55 parts by weight of fine iron ore, and crushing and grinding until the particle size is 1mm to prepare mixed ore powder;
grinding limestone until the particle size is less than 3 mu m to prepare ultrafine particle limestone, mixing the ultrafine particle limestone with mixed mineral powder, adding bonded bentonite, uniformly mixing to prepare a roasting material, pelletizing the roasting material, screening to obtain green pellets, and roasting, wherein the dosage of the bonded bentonite is controlled to be 1% of the weight of the roasting material.
The third step of roasting comprises drying, preheating, roasting, soaking and cooling; oxygen enrichment is carried out in the preheating and roasting processes, the oxygen content in the preheating process is kept at 15%, and the oxygen content in the roasting process is kept at 12%.
The iron content of the refined iron ore is more than 75%.
The adhesive bentonite comprises the following steps:
s1, placing bentonite into a sulfuric acid solution with the concentration of 1mol/L, heating in a water bath at 60 ℃, stirring for 12 hours, filtering, washing to be neutral by deionized water, then drying for 10 hours in vacuum, grinding, and sieving by a 100-mesh sieve to prepare a sample for later use, wherein the dosage ratio of the bentonite to the sulfuric acid solution is 5 g: 200 mL;
step S2, adding the prepared sample into the mixed solution, stirring at a constant speed for 10min, adding 3-aminopropyltriethoxysilane, heating to 65 ℃, carrying out reflux reaction for 12h, cooling to room temperature after the reaction is finished, carrying out suction filtration, washing for three times, carrying out vacuum drying for 10h, grinding, and sieving with a 200-mesh sieve to obtain a primary material, wherein the dosage ratio of the sample, the mixed solution and the 3-aminopropyltriethoxysilane is 5 g: 150 mL: 5 g;
step S3, adding aniline into a sodium citrate aqueous solution with the mass fraction of 20%, adding a primary material after uniform dispersion, continuing to disperse for 10min, cooling to 10 ℃, dropwise adding an ammonium persulfate aqueous solution with the mass fraction of 10% while stirring, controlling the dropwise adding time to be 30min, stirring after complete dropwise addition, reacting for 10h, performing suction filtration after the reaction is finished, performing vacuum drying for 10h after washing for three times, grinding, and sieving with a 200-mesh sieve to obtain the cohesive bentonite, wherein the dosage ratio of the aniline, the sodium citrate aqueous solution, the primary material and the ammonium persulfate aqueous solution is 3 g: 200 mL: 3 g: 8 mL.
The mixed solution is formed by mixing absolute ethyl alcohol and deionized water according to the volume ratio of 70: 30.
Example 5
A method for improving the compressive strength of an alkaline pellet ore prepared with limestone comprises the following steps:
adding 2.5 parts by weight of anhydrous magnesium sulfate and 17.12 parts by weight of urea into deionized water, uniformly stirring, adding 0.2 part by weight of sodium polyacrylate, magnetically stirring for 1h to obtain a mixed solution, transferring the mixed solution into a reaction kettle, uniformly stirring at 150 ℃, reacting for 6h, cooling to room temperature after the reaction is finished, filtering, washing and drying to obtain a precursor, placing the precursor into a muffle furnace, roasting at 500 ℃ for 5h, and cooling to obtain treated magnesium oxide;
step two, uniformly mixing 0.5 part by weight of the treated magnesium oxide, 2.3 parts by weight of calcium oxide and 55 parts by weight of fine iron ore, and crushing and grinding until the particle size is 1mm to prepare mixed ore powder;
grinding limestone until the particle size is less than 3 mu m to prepare ultrafine particle limestone, mixing the ultrafine particle limestone with mixed mineral powder, adding bonded bentonite, uniformly mixing to prepare a roasting material, pelletizing the roasting material, screening to obtain green pellets, and roasting, wherein the dosage of the bonded bentonite is controlled to be 1% of the weight of the roasting material.
The third step of roasting comprises drying, preheating, roasting, soaking and cooling; oxygen enrichment is carried out in the preheating and roasting processes, the oxygen content in the preheating process is kept at 15%, and the oxygen content in the roasting process is kept at 12%.
The iron content of the refined iron ore is more than 75%.
The adhesive bentonite comprises the following steps:
s1, placing bentonite into a sulfuric acid solution with the concentration of 1mol/L, heating in a water bath at 60 ℃, stirring for 12 hours, filtering, washing to be neutral by deionized water, then drying for 10 hours in vacuum, grinding, and sieving by a 100-mesh sieve to prepare a sample for later use, wherein the dosage ratio of the bentonite to the sulfuric acid solution is 58 g: 220 mL;
step S2, adding the prepared sample into the mixed solution, stirring at a constant speed for 10min, adding 3-aminopropyltriethoxysilane, heating to 65 ℃, carrying out reflux reaction for 12h, cooling to room temperature after the reaction is finished, carrying out suction filtration, washing for three times, carrying out vacuum drying for 10h, grinding, and sieving with a 200-mesh sieve to obtain a primary material, wherein the dosage ratio of the sample, the mixed solution and the 3-aminopropyltriethoxysilane is 5 g: 150 mL: 5 g;
step S3, adding aniline into a sodium citrate aqueous solution with the mass fraction of 20%, adding a primary material after uniform dispersion, continuing to disperse for 10min, cooling to 10 ℃, dropwise adding an ammonium persulfate aqueous solution with the mass fraction of 10% while stirring, controlling the dropwise adding time to be 30min, stirring after complete dropwise addition, reacting for 10h, performing suction filtration after the reaction is finished, performing vacuum drying for 10h after washing for three times, grinding, and sieving with a 200-mesh sieve to obtain the cohesive bentonite, wherein the dosage ratio of the aniline, the sodium citrate aqueous solution, the primary material and the ammonium persulfate aqueous solution is 5 g: 220 mL: 5 g: 8 mL.
The mixed solution is formed by mixing absolute ethyl alcohol and deionized water according to the volume ratio of 70: 30.
Example 6
A method for improving the compressive strength of an alkaline pellet ore prepared with limestone comprises the following steps:
adding 2.5 parts by weight of anhydrous magnesium sulfate and 17.12 parts by weight of urea into deionized water, uniformly stirring, adding 0.2 part by weight of sodium polyacrylate, magnetically stirring for 1h to obtain a mixed solution, transferring the mixed solution into a reaction kettle, uniformly stirring at 150 ℃, reacting for 6h, cooling to room temperature after the reaction is finished, filtering, washing and drying to obtain a precursor, placing the precursor into a muffle furnace, roasting at 500 ℃ for 5h, and cooling to obtain treated magnesium oxide;
step two, uniformly mixing 0.5 part by weight of the treated magnesium oxide, 2.3 parts by weight of calcium oxide and 55 parts by weight of fine iron ore, and crushing and grinding until the particle size is 1mm to prepare mixed ore powder;
grinding limestone until the particle size is less than 3 mu m to prepare ultrafine particle limestone, mixing the ultrafine particle limestone with mixed mineral powder, adding bonded bentonite, uniformly mixing to prepare a roasting material, pelletizing the roasting material, screening to obtain green pellets, and roasting, wherein the dosage of the bonded bentonite is controlled to be 1% of the weight of the roasting material.
The third step of roasting comprises drying, preheating, roasting, soaking and cooling; oxygen enrichment is carried out in the preheating and roasting processes, the oxygen content in the preheating process is kept at 15%, and the oxygen content in the roasting process is kept at 12%.
The iron content of the refined iron ore is more than 75%.
The adhesive bentonite comprises the following steps:
s1, placing bentonite into a sulfuric acid solution with the concentration of 1mol/L, heating in a water bath at 60 ℃, stirring for 12 hours, filtering, washing to be neutral by deionized water, then drying for 10 hours in vacuum, grinding, and sieving by a 100-mesh sieve to prepare a sample for later use, wherein the dosage ratio of the bentonite to the sulfuric acid solution is 10 g: 250 mL;
step S2, adding the prepared sample into the mixed solution, stirring at a constant speed for 10min, adding 3-aminopropyltriethoxysilane, heating to 80 ℃, carrying out reflux reaction for 12h, cooling to room temperature after the reaction is finished, carrying out suction filtration, washing for three times, carrying out vacuum drying for 10h, grinding, and sieving with a 200-mesh sieve to obtain a primary material, wherein the dosage ratio of the sample, the mixed solution and the 3-aminopropyltriethoxysilane is 5 g: 150 mL: 5 g;
step S3, adding aniline into a sodium citrate aqueous solution with the mass fraction of 20%, adding a primary material after uniform dispersion, continuing to disperse for 10min, cooling to 10 ℃, dropwise adding an ammonium persulfate aqueous solution with the mass fraction of 10% while stirring, controlling the dropwise adding time to be 30min, stirring after complete dropwise addition, reacting for 10h, performing suction filtration after the reaction is finished, performing vacuum drying for 10h after washing for three times, grinding, and sieving with a 200-mesh sieve to obtain the cohesive bentonite, wherein the dosage ratio of the aniline, the sodium citrate aqueous solution, the primary material and the ammonium persulfate aqueous solution is 5 g: 250 mL: 5 g: 10 mL.
The mixed solution is formed by mixing absolute ethyl alcohol and deionized water according to the volume ratio of 70: 30.
Comparative example 2
This comparative example compares to example 4 with bentonite instead of the bound bentonite.
The compressive strength of the alkaline pellets of examples 4 to 6 and comparative example 2 was measured according to the national standard GB/T14201-93 "method for measuring compressive strength of iron ore pellets", and the results are shown in Table 2 below;
TABLE 2
| Example 4 | Example 5 | Example 6 | Comparative example 2 | |
| Compressive strength N/P | 2855±8 | 2853±8.5 | 2850±7.8 | 2843±10 |
As can be seen from the above tables 1 and 2, the present invention, by performing the preliminary treatment on the magnesium oxide, allows the magnesium oxide itself to have a high porosity, oxygen can enter the pellet through the pores in the oxygen enrichment process, so that the oxidation of iron ore particles is increased, the compressive strength of the pellet is improved, and a layer of polymer is grafted on the surface of the bentonite, so that the interlayer spacing of the bentonite is enlarged, the specific surface area of the bentonite is increased, adsorption sites are increased, in addition, the polymer is heated and decomposed in the roasting process, so that the 'bonding' effect of the bonding bentonite and other raw materials is further increased, the roasting is facilitated, the uniform stability of the roasted alkaline pellets is improved, and then improve its compressive strength, its great interlamellar spacing further lets oxygen get into inside the pelletizing through high interlamellar spacing in the oxygen boosting process moreover, further increases the oxidation of iron ore granule, and then improves the compressive strength of pellet.
In the description herein, references to the description of "one embodiment," "an example," "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The foregoing is illustrative and explanatory only and is not intended to be exhaustive or to limit the invention to the precise embodiments described, and various modifications, additions, and substitutions may be made by those skilled in the art without departing from the scope of the invention or exceeding the scope of the claims.
Claims (6)
1. A method for improving the compressive strength of an alkaline pellet ore prepared with limestone is characterized by comprising the following steps:
adding 2.5-3.0 parts by weight of anhydrous magnesium sulfate and 17.12-17.56 parts by weight of urea into deionized water, uniformly stirring, adding 0.2-0.5 part by weight of sodium polyacrylate, magnetically stirring for 1h to prepare a mixed solution, transferring the mixed solution into a reaction kettle, uniformly stirring at a constant speed at 180 ℃ for 6h, cooling to room temperature after the reaction is finished, filtering, washing and drying to prepare a precursor, then placing the precursor into a muffle furnace, roasting at 550 ℃ for 5h, and cooling to prepare treated magnesium oxide;
step two, uniformly mixing 0.5 to 2.0 weight parts of treated magnesium oxide, 2.3 to 3.5 weight parts of calcium oxide and 55 to 70 weight parts of fine iron ore, crushing and grinding until the particle size is 1 to 5mm, and preparing mixed ore powder;
grinding limestone until the particle size is less than 3 mu m to prepare ultrafine particle limestone, mixing the ultrafine particle limestone with mixed mineral powder, adding bonded bentonite, uniformly mixing to prepare a roasting material, pelletizing the roasting material, screening to obtain green pellets, and roasting, wherein the dosage of the bonded bentonite is controlled to be 1-2.5% of the weight of the roasting material.
2. The method for improving the compressive strength of alkaline pellets with limestone as claimed in claim 1, wherein the roasting in the third step comprises drying, preheating, roasting, soaking and cooling; oxygen enrichment is carried out in the preheating and roasting processes, the oxygen content in the preheating process is kept between 15 and 18 percent, and the oxygen content in the roasting process is kept between 12 and 16 percent.
3. The method for improving the compressive strength of alkaline pellets with limestone as claimed in claim 1, wherein the iron content of the fine iron ore is more than 75%.
4. The method for improving the compressive strength of alkaline pellets with limestone as claimed in claim 1, wherein the binding bentonite comprises the steps of:
step S1, placing bentonite into a sulfuric acid solution with the concentration of 1mol/L, heating in a water bath at 45-60 ℃, stirring for 12 hours, filtering, washing with deionized water to be neutral, then drying in vacuum for 10 hours, grinding, and sieving with a 100-mesh sieve to obtain a sample for later use;
step S2, adding the prepared sample into the mixed solution, stirring at a constant speed for 10min, adding 3-aminopropyltriethoxysilane, heating to 65-80 ℃, carrying out reflux reaction for 12h, cooling to room temperature after the reaction is finished, carrying out suction filtration, washing for three times, carrying out vacuum drying for 10h, grinding, and sieving with a 200-mesh sieve to obtain a primary material;
and step S3, adding aniline into the sodium citrate aqueous solution, adding the primary material after uniform dispersion, continuously dispersing for 10min, cooling to 0-10 ℃, dropwise adding the ammonium persulfate aqueous solution while stirring, controlling the dropwise adding time to be 30min, stirring after complete dropwise addition, reacting for 10h, after the reaction is finished, performing suction filtration, washing for three times, performing vacuum drying for 10h, grinding, and sieving with a 200-mesh sieve to obtain the adhesive bentonite.
5. The method for improving the compressive strength of alkaline pellets with limestone as claimed in claim 4, wherein the mixed solution is formed by mixing absolute ethyl alcohol and deionized water according to a volume ratio of 70: 30.
6. The method as claimed in claim 4, wherein the amount ratio of the bentonite to the sulfuric acid solution in step S1 is 5-10 g: 200-250mL, the amount ratio of the sample, the mixed solution and the 3-aminopropyltriethoxysilane in step S2 is 5 g: 150 mL: 5g, and the amount ratio of the aniline, the aqueous solution of sodium citrate, the primary material and the aqueous solution of ammonium persulfate in step S3 is 3-5 g: 200-250 mL: 3-5 g: 8-10 mL.
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