Iron ore cold-bonded pellet, raw material for pellet and preparation method of raw material

Abstract

The invention discloses an iron ore cold-bonded pellet, a raw material for the pellet and a preparation method of the pellet, and belongs to the technical field of cold-bonded pellet preparation. According to the iron ore cold-bonded pellet, pellet raw materials comprise mineral components, Na2O.nSiO2 and CaCl2, the mineral components comprise, by mass, 45-65 parts of sintering return mine and 35-55 parts of magnetite concentrate, and the addition amount of Na2O.nSiO2 and the addition amount of CaCl2 account for (4-5)% and (4-5)% of the total amount of the mineral components respectively. According to the preparation method, the magnetite concentrate and the sintering return mine are compounded, and Na2O.nSiO2 is used as an adhesive, so that the strength of the obtained cold-bonded pellets can be effectively improved; meanwhile, by adding CaCl2, sodium ions of Na2O.nSiO2 can be replaced, and the situation that the content of alkali metal in the pellets is too high is prevented.

Description

Technical Field

[0001] The invention belongs to the technical field of cold consolidation pellet preparation, and more specifically, relates to an iron ore cold consolidation pellet, a raw material for the pellet and a preparation method thereof. Background Art

[0002] The production process of sintered ore is energy-intensive and polluting, and it also produces return ore, which accounts for 30% to 40% of the total sintering volume. The current treatment method for these sintered return ore is to return them to the sintering process for re-sintering. In order to treat sintered return ore in a green and efficient manner, it is of great significance to effectively combine it with cold consolidation pellet technology to prepare a new type of blast furnace charge - sintered return ore cold consolidation pellets.

[0003] Cold consolidation pelletizing technology has attracted extensive attention in the field of metallurgical solid waste treatment and new furnace charge preparation due to its significant energy-saving effect. Nowadays, cold consolidation pelletizing is mainly used in processes such as rotary hearth furnaces and converters that have relatively low requirements for cold and hot strength. There are few reports on the research of cold consolidation pelletizing technology for blast furnaces. The blast furnace requires the strength of cold consolidation pellets to be above 2000N, but the particle size distribution of sintered return ore is uneven, and it is difficult to press or pelletize pure sintered return ore. For this reason, adding a small amount of hematite concentrate with better reducibility to the sintered return ore can improve its molding performance, but the pellets obtained by molding have problems such as unstable cold strength, poor hot strength and reduction pulverization performance. At the same time, when entering the blast furnace, it will block the gaps in the material column, hinder the flow of coal gas in the blast furnace to the top of the furnace, and affect the smooth production of the blast furnace.

[0004] Inorganic binders, such as bentonite, silicate cement and water glass, have the advantages of strong bonding force, low cost and good hydrophilicity. They can effectively improve the cold strength of cold-consolidated pellets and meet the strength requirements of pellets entering blast furnaces. Among them, cold-consolidated pellets of iron ore powder, manganese ore powder and other mineral powders prepared with water glass as a binder have good strength at room temperature and high temperature, less impurities are introduced during the preparation process, and the strength can meet the requirements of large blast furnace smelting. It is a kind of cold-consolidated pellets that are widely used in my country. However, due to the large amount of alkali metals introduced and poor water and moisture resistance, its application is hindered. Therefore, while ensuring the strength of sintered cold-consolidated pellets, the problem of alkali metal removal remains to be solved.

[0005] After searching, a Chinese patent (CN102628099 A) discloses a method for preparing cold-consolidated pellets of mineral powder using water glass as a binder. The application uses a strong alkali (NaOH) to modify the mineral powder and adds water glass to prepare cold-consolidated pellets, thereby improving the strength of the pellets. However, the problem of alkali metal introduction has not been effectively solved.

[0006] A Chinese patent (CN114717412 A) discloses a binder for cold-pressed pellets, cold-pressed pellets and a preparation method thereof, but the binder has a good binding effect on fine-grained concentrates, but has little effect on coarse-grained ore powder (such as sintered powder ore).

[0007] Chinese patent (CN 1537959A) discloses a cold-consolidated pellet ore for blast furnace ironmaking and a preparation method thereof, wherein the iron-containing materials used are one or more of rotary hearth furnace dust removal mud, vertical furnace, sintering dust removal ash, steel rolling oxide scale, ironmaking undersize, magnetic steel slag powder, magnetic iron slag powder, and concentrate powder, and do not involve iron-containing resources of sintering return ore. Summary of the invention

[0008] The purpose of the present invention is to provide an iron ore cold consolidation pellet, a raw material for pellets and a preparation method thereof, so as to solve the technical problem that sintered return ore is difficult to utilize in the prior art. The present invention uses sintered return ore as the main raw material, adds a certain amount of magnetite concentrate, and uses Na 2 O·nSiO 2 As a bonding agent, supplemented with CaCl 2 The sintered ore can be modified so that it can be effectively used in the production of blast furnace cold-consolidated pellets, which can not only ensure the molding strength of the obtained pellets, but also avoid the adverse effects of alkali metal Na in the binder.

[0009] In order to achieve the above object, the technical solution provided by the present invention is:

[0010] The first aspect of the present invention provides a raw material for cold consolidation pelletization of iron ore, comprising a mineral component, Na 2 O·nSiO 2 and CaCl 2 , wherein the mineral components include 45 to 65 parts by mass of sintered return ore and 35 to 55 parts by mass of magnetite concentrate, and Na 2 O·nSiO 2 and CaCl 2 The added amounts account for (4-5)% and (4-5)% of the total mineral components respectively.

[0011] Based on the problem that sintered return ore is difficult to be effectively used in blast furnace cold consolidation pellets in the prior art, the present invention combines magnetite concentrate with sintered return ore as the skeleton of cold consolidation pellets, and supplements with Na 2 O·nSiO 2 As a binder, it can enhance the molding strength, thereby significantly improving the strength of the cold-consolidated pellets. 2 O·nSiO 2 The alkali metal content is relatively high, which affects the water and moisture resistance of the pellets. On this basis, the present invention further adds a certain amount of CaCl 2, Ca ions can replace Na 2 O·nSiO 2 The Na ions in the pellets are converted into water-insoluble calcium silicate, which, on the one hand, is beneficial to further improve the strength of the pellets; on the other hand, part of the NaCl will be squeezed out along with the water during the pelletizing process, thereby reducing the alkali metal content in the pellets.

[0012] Preferably, the Na 2 O·nSiO 2 The modulus n is between 2.3 and 2.5.

[0013] Adhesive Na 2 O·nSiO 2 The modulus n refers to the molecular ratio or molar ratio of silicon dioxide to alkali metal oxide, the binder Na 2 O·nSiO 2 The bonding force of the water glass increases first and then decreases with the increase of the modulus. If the modulus is too small, the bonding force is too small, and the strength improvement effect of the cold-consolidated pellets becomes low. However, when the modulus is too high, the solubility of the water glass becomes poor, and it is difficult to disperse evenly in the solution. + Encapsulated, CaCl 2 with Na + The contact reaction is hindered, which is not conducive to the reaction and affects the removal of alkali metals. In addition, the curing speed is too fast, resulting in insufficient contact and reaction with the material particles, and the bonding force is reduced. 2 O·nSiO 2 The modulus n is optimized to ensure better bonding effect, which is beneficial to further improve the strength of the pellets; on the other hand, it can prevent Na + With CaCl 2 The replacement reaction between them is hindered, thereby preventing the removal effect of alkali metal Na from being affected.

[0014] Preferably, the mass proportions of the sintered return ore with particle sizes of 0-1mm, 1mm-2mm, 2mm-3mm, 3mm-4mm and 4mm-5mm are 38-53%, 16-20%, 12-16%, 9-14% and 8-13% respectively, and the grading index is preferably 0.4-0.6.

[0015] The present invention further optimizes the particle grading of the sintered return ore so that the particle distribution of the sintered return ore presents a discontinuous characteristic, eliminates the gaps caused by the blocking and supporting effects of smaller particles, and minimizes the void ratio of the aggregate. This graded mixture has both a certain amount of coarse aggregate and a sufficient amount of fine aggregate filling, has the advantages of a higher internal friction angle and cohesion, a small void ratio, and a small surface area, and has a more significant skeleton effect, so that the binder can be effectively saved.

[0016] Preferably, the raw materials of the mixture include water, and the amount of water added accounts for 6-8% of the total amount of mineral components.

[0017] The second aspect of the present invention provides a cold-consolidated iron ore pellet, wherein the pellet raw material is the pellet raw material of any technical solution of the first aspect of the present invention.

[0018] Preferably, the pellets are obtained by pelletizing and pre-baking the raw materials of any technical solution of the first aspect of the present invention. By further pre-baking the pellets, on the one hand, part of the NaCl can be further volatilized, and generally, more than 50% of the alkali metals can be removed; on the other hand, the magnetite concentrate will form hematite crystals during the pre-baking process, which is conducive to further improving the strength of the pellets and compensating for the significant decrease in the strength of the pellets caused by the brittleness of the binder during the heating process.

[0019] Preferably, after pre-calcination, TFe, FeO, SiO 2 、Al 2 O 3 , CaO, MgO, K 2 The mass proportions of O+NaO are 55-65%, 0.5-1.0%, 4-8%, 1-3%, 5-7%, 1-3% and 0-0.2% respectively.

[0020] Preferably, the pre-baking temperature is 920±5° C. and the pre-baking time is 10 to 12 minutes, so as to ensure the removal effect of alkali metals and the compensation effect on the pellet strength.

[0021] Preferably, the cold consolidation strength of the pellets is above 2000N / Pellet, which can meet the use requirements of a blast furnace.

[0022] The third aspect of the present invention provides a method for preparing cold-consolidated pellets, comprising:

[0023] Any pelletizing material according to the first aspect of the present invention is subjected to a pelletizing treatment to obtain pellets.

[0024] Preferably, the method further comprises: pre-baking the pellets obtained by the pelletizing to obtain finished pellets.

[0025] Preferably, a tablet press is used to press the pellet raw materials into pellets, and the molding pressure is 55-60 MPa;

[0026] and / or the pre-baking temperature is 920±5°C and the pre-baking time is 10 to 12 minutes;

[0027] And / or after pelletizing, the obtained pellets are dried and then pre-calcined.

[0028] In summary, the technical solution provided by the present invention can achieve the following beneficial effects compared with the prior art:

[0029] (1) The present invention combines magnetite concentrate with sintered return ore and adds Na 2 O·nSiO 2 As a binder, the strength of the cold-consolidated pellets can be effectively improved to meet the requirements of blast furnace use (strength higher than 2000N / Pellet), and the resource recycling of sintered ore can be realized; at the same time, the present invention uses CaCl 2 The addition of 2 O·nSiO 2 Sodium ions are removed to prevent the alkali metal content in the pellets from being too high.

[0030] (2) The present invention further provides the adhesive Na 2 O·nSiO 2 The modulus is optimized to ensure effective bonding and further increase the strength of the pellets, while also ensuring the removal of alkali metals.

[0031] (3) According to the grading theory, the present invention re-screens and grades the sintered return ore raw materials, prepares the sintered return ore with ideal particle size, and uses the composite combination of magnetite concentrate and the sintered return ore with ideal particle size as the cold-solidified pellet skeleton, which can not only greatly improve the strength of the cold-solidified pellets, but also effectively reduce the amount of binder used, which is beneficial to cost saving.

[0032] (4) The present invention further pre-calcines the pellets obtained by ball making, thereby further improving the removal effect of alkali metal sodium. At the same time, the magnetite concentrate can be used to form hematite crystals during the heating process to improve the strength, thereby compensating for the decrease in pellet strength caused by the brittleness of the binder during the heating process. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The schematic diagram of the internal structure of cold-consolidated pellets of sintered return ore with different particle size distributions;

[0034] Figure 2 Schematic diagram of the effect of the modulus n of the adhesive on the alkali metal ion replacement reaction in the adhesive. DETAILED DESCRIPTION

[0035] The present invention is based on the combination of sintered return ore and magnetite concentrate, and uses inorganic binders to enhance the molding strength to form a new type of cold-consolidated pelletized charge, which is conducive to building an efficient, clean and low-consumption blast furnace charge structure, and provides strong support for the green and sustainable development of the steel industry.

[0036] Specifically, the present invention provides a mixture for cold consolidation pelletizing, the raw materials of the mixture include mineral components, Na2 O·nSiO 2 and CaCl 2 , wherein the mineral components include 45 to 65 parts by mass of sintered return ore and 35 to 55 parts by mass of magnetite concentrate, and Na 2 O·nSiO 2 and CaCl 2 The added amounts account for (4-5)% and (4-5)% of the total mineral components respectively.

[0037] The raw materials including the above-mentioned mixed materials are pelletized to produce cold-consolidated pellets. After the pellets are pressed and formed, they are placed in a drying oven for drying or dehydrated under natural conditions to finally obtain cold-consolidated pellets. As a further preferred embodiment, the dried cold-consolidated pellets are pre-baked at 920±5°C for 10 to 12 minutes to finally obtain the finished product. After the pre-baking treatment, TFe, FeO, SiO 2 、Al 2 O 3 , CaO, MgO, K 2 The mass proportions of O+NaO are preferably 55-65%, 0.5-1.0%, 4-8%, 1-3%, 5-7%, 1-3%, and 0-0.2%, respectively.

[0038] The main chemical composition range of the raw material sintered return ore used in the present invention is shown in Table 1 below, but its composition is not limited, and sintered return ore composed of other components can also be used.

[0039] Table 1 Main chemical composition range of sintered ore (wt.%)

[0040]

[0041] As shown in Table 2 below, the sintered return ore is screened and graded according to different grading indexes m according to the particle size: 0-1mm, 1mm-2mm, 2mm-3mm, 3mm-4mm, 4mm-5mm. When the grading index m is 0.4-0.6, that is, the particle grading in No. 2-4 is adopted, the void ratio of the aggregate can be effectively reduced, which is beneficial to improve the strength of the pellets and reduce the amount of adhesive. The sintered return ore with a particle size grading of No. 3 is further preferred. The cold-consolidated pellets prepared by combining the sintered return ore with this grading and the magnetite concentrate have the best strength. Figure 1 It can also be clearly seen that the cold-solidified pellets formed by compounding the sintered return ore and the magnetite concentrate under the grading index m of the present invention have a significantly lower porosity and a significantly improved compactness than the pellets made from the ungraded sintered return ore and the pellets made entirely from the graded sintered return ore (without adding the magnetite concentrate). It is further preferred that when the sintered return ore and the magnetite concentrate are compounded, the magnetite concentrate is directly used to replace the sintered return ore with a particle size of 0-1.

[0042] Table 2 Sintering return ore grading scheme

[0043]

[0044] In order to further understand the content of the present invention, the present invention is now described in detail in conjunction with specific embodiments. However, due to limited space, only some embodiments are listed, and the actual protection scope, especially the specific mass proportion of each component, the chemical composition of the sintered return ore and the magnetite concentrate, the particle size distribution, etc. are not limited to the following specific embodiments.

[0045] Example 1

[0046] The cold consolidation pelletizing mixture of this embodiment comprises mineral components, Na 2 O·nSiO 2 , CaCl 2 and water, wherein the mineral components include 45 parts by mass of sintered return ore and 55 parts by mass of magnetite concentrate, and Na 2 O·nSiO 2 , CaCl 2 The added amounts of mineral components, water and mineral matter account for 4%, 4% and 7% of the total mineral components respectively.

[0047] Specifically, the chemical composition of the raw material sintering return ore in this embodiment is shown in Table 3, and its particle size distribution is prepared according to the No. 3 scheme in Table 2; the iron grade of the magnetite concentrate M is 65.75%, the FeO content is 26.50%, and the SiO 2 The content is 6.57%, and the particle size is less than 1mm; the Na 2 O·nSiO 2 The modulus n is 2.5.

[0048] Table 3 Chemical composition of sintered ore (wt.%)

[0049]

[0050] The method for preparing the cold-consolidated pellets of this embodiment specifically comprises the following steps:

[0051] Step 1: Screen and grade the raw material sintered ore, and prepare the sintered ore particles according to the grading requirements;

[0052] Step 2: Mix various raw materials of the pelletizing mixture in proportion to prepare a mixture;

[0053] Step 3: Preparation of cold-consolidated pellets;

[0054] In this embodiment, the cold-pressed pellets are prepared by a ZYP-20TS fully automatic powder tablet press, and the molding pressure is set to 60 MPa. After the pellets are pressed and formed, they are placed in a 105° C. drying oven for drying or dehumidified under natural conditions to finally obtain cold-consolidated pellets.

[0055] Step 4: pre-baking the cold-consolidated pellets obtained in step 3 at 925°C for 10 minutes to obtain the finished product. 2 、Al 2 O 3 , CaO, MgO, K 2 The mass proportions of O+NaO are 57.57%, 0.89%, 7.85%, 1.87%, 6.25%, 1.80% and 0.17% respectively.

[0056] Comparative Example 1 (Sintering return ore + water)

[0057] Compared with Example 1, this comparative example uses pure sintered return ore + 7% water (mass percentage relative to the mineral components) as pellet raw material. Pure sintered return ore is difficult to be directly pressed into pellets and has almost no strength.

[0058] Comparative Example 2 (Sintered return ore + magnetite concentrate + water)

[0059] Compared with Example 1, this comparative example uses 45% sintered return ore and 55% magnetite concentrate as mineral components without using a binder, and additionally adds 7% water by weight of the mineral components to make pellets, and the obtained pellets are not pre-calcined. However, the strength of the prepared cold-consolidated pellets still cannot meet the blast furnace production requirements (2000N / Pellet).

[0060] Comparative Example 3 (Sintered return ore + magnetite concentrate + Na 2 O·nSiO 2 + water)

[0061] This comparative example is based on comparative example 2, and Na 2 O·nSiO 2 As a binder, and the obtained pellets are not pre-calcined, the strength of the finally prepared cold-consolidated pellets is improved, but the strength is still not stable above 2000N / Pellet.

[0062] The strength data of the cold-solidified pellets prepared in Example 1 and Comparative Examples 1-3 are specifically shown in Table 4 below. Combined with Table 4, it can be seen that the technical solution of the embodiment can effectively improve the strength of the obtained cold-solidified pellets and ensure the stability of the pellet strength, so that the pellet strength can be stabilized at more than 2000N / Pellet.

[0063] Specifically, the strength of cold-set pellets can be effectively improved by adding adhesives. However, in order to ensure the strength of cold-set pellets, the amount of adhesive used is 4-5%, resulting in a high alkali metal content. Alkali metals have the following adverse effects on blast furnace production: ① Advance and aggravate CO 2 ① The gasification reaction of coke reduces the indirect reduction zone and expands the direct reduction zone, which in turn causes an increase in the coke ratio; it reduces the particle size and strength of the coke, thereby reducing the permeability of the material column, especially the air window of the soft melting zone, causing damage to the tuyere. ② It causes abnormal expansion of the pelletized ore (even catastrophic expansion), which reduces its strength and increases the powdering rate, bringing adverse effects on blast furnace smelting. ③ It causes abnormal expansion of silicon-aluminum refractory materials, spalling and severe erosion of the hot surface, which greatly reduces the life of the blast furnace lining, and in severe cases, it will also crack the steel shell of the furnace bottom. ④ In blast furnaces with serious accumulation of alkali metals, due to the reduction of the soft melting temperature of the ore, the coke is severely damaged, the airflow distribution is abnormal, or the cooling intensity is too high, which causes nodules in the middle and upper parts of the blast furnace.

[0064] To solve this problem, the present invention further adds 4-5% CaCl to the original ingredients. 2 Calcium chloride is used to undergo a replacement reaction with an alkali metal binder, and the pellets are pre-baked and cold-solidified in coordination, thereby effectively removing the alkali metal Na and consolidating the pellet strength.

[0065] Principle: Na 2 O·nSiO 2 +CaCl 2 →CaO·nSiO 2 +2NaCl, Ca ions replace Na ions to produce water-insoluble calcium silicate, further improving the strength of the pellets; at the same time, under the pressure of 55-60Mpa, part of the NaCl is squeezed out with the water. By further pre-roasting the pellets, some NaCl will volatilize under the pre-roasting conditions. In general, more than 50% of the alkali metals are removed. In addition, the magnetite concentrate will form hematite crystals during the pre-roasting process to improve the strength of the pellets, solving the problem of a significant decrease in the strength of the pellets caused by the binder becoming brittle and fragile during the heating process.

[0066] Table 4 Comparison of the strength of the cold-consolidated pellets prepared in Example 1 and Comparative Examples 1-3

[0067]

[0068]

[0069] Example 2

[0070] The preparation method of cold-consolidated pellets in this embodiment is different from that in Example 1 mainly in that: Na 2 O·nSiO2 The modulus n is 2.3.

[0071] Example 3

[0072] The preparation method of cold-consolidated pellets in this embodiment is different from that in Example 1 mainly in that: Na 2 O·nSiO 2 The modulus n is 2.4.

[0073] Comparative Example 4

[0074] The cold-consolidated pellets of this comparative example are different from those of Example 1 mainly in that: the Na 2 O·nSiO 2 The modulus n is 1.5.

[0075] Comparative Example 5

[0076] The cold-consolidated pellets of this comparative example are different from those of Example 1 mainly in that: the Na 2 O·nSiO 2 The modulus n is 2.

[0077] Comparative Example 6

[0078] The cold-consolidated pellets of this comparative example are different from those of Example 1 mainly in that: the Na 2 O·nSiO 2 The modulus n is 3.

[0079] The strength data of the pellets prepared in Example 2, Example 3 and Comparative Examples 4-6 are shown in Table 5. It can be seen from the data in the table that the modulus of the adhesive is too small, the bonding force of the water glass is too small, and the strength improvement effect of the cold consolidated ball is low; the modulus is too large, Na + Encapsulated, CaCl 2 with Na + Contact reaction is hindered (binding Figure 2 ), which is not conducive to the reaction and affects the removal of alkali metals. Therefore, the modulus of the adhesive used is preferably 2.3-2.5.

[0080] Table 5 Effect of water glass modulus on strength and sodium removal rate

[0081]

[0082] Example 4

[0083] The preparation method of cold-consolidated pellets in this embodiment is different from that in Example 1 mainly in that the mineral components in this embodiment include 55 parts by mass of sintered return ore and 45 parts by mass of magnetite concentrate, and the particle size distribution of the sintered return ore is prepared according to the No. 2 scheme in Table 2, Na2 O·nSiO 2 , CaCl 2 The addition amount of water accounts for 5%, 5% and 8% of the total mineral components respectively, and the molding pressure of the pressing and molding is 58MPa. The pellets are dried at 110℃ and then pre-calcined. The pre-calcination temperature is 920℃ and the pre-calcination time is 12min.

[0084] Example 5

[0085] The preparation method of cold-consolidated pellets in this embodiment is different from that in Example 1 mainly in that the mineral components in this embodiment include 65 parts by mass of sintered return ore and 35 parts by mass of magnetite concentrate, and the particle size distribution of the sintered return ore is prepared according to the No. 4 scheme in Table 2, Na 2 O·nSiO 2 , CaCl 2 The addition amount of water accounts for 4.5%, 4.5% and 7.5% of the total mineral components respectively, and the molding pressure of the pressing and molding is 55MPa. The pellets are dried at 110℃ and then pre-calcined. The pre-calcination temperature is 915℃ and the pre-calcination time is 11min.

[0086] Comparative Example 7

[0087] The preparation method of the cold-consolidated pellets in this comparative example is basically the same as that in Example 1, except that the pellets in this example are not pre-baked after being pelletized and dried.

[0088] Comparative Example 8

[0089] The preparation method of cold-consolidated pellets in this comparative example is different from that in Example 1 mainly in that no CaCl is added to the pellet mixture in this comparative example. 2 .

[0090] The strength data of the pellets prepared in Comparative Examples 7 and 8 are shown in Table 6 below. It can be seen that the strength of the cold-pressed pellets without pre-baking cannot be stabilized above 2000N / Pellet, especially the sodium removal rate is low, which cannot meet the requirements of blast furnace smelting. 2 Although the pellet strength can meet the requirements of blast furnace smelting, the sodium removal rate is low. Therefore, adding CaCl 2 The two conditions of pre-roasting need to be met at the same time, so that the strength and sodium removal rate of the pellets can be met.

[0091] Table 6 Strength and sodium removal rate of cold pressed pellets without pre-baking

[0092]

Claims

1. A raw material for cold consolidation pelletizing of iron ore, characterized in that: It comprises mineral components, Na2O·nSiO2 and CaCl2, wherein the mineral components comprise 45-65 parts by mass of sintered return ore and 35-55 parts by mass of magnetite concentrate, and the added amounts of Na2O·nSiO2 and CaCl2 account for (4-5)% and (4-5)% of the total amount of the mineral components respectively.

2. The pelletizing raw material according to claim 1, characterized in that: The modulus n of the Na2O·nSiO2 is 2.3 to 2.

5.

3. The pelletizing raw material according to claim 1, characterized in that: The mass proportions of the sintered return ore with particle sizes of 0-1mm, 1mm-2mm, 2mm-3mm, 3mm-4mm and 4mm-5mm are 38-53%, 16-20%, 12-16%, 9-14% and 8-13% respectively, and the grading index is 0.4-0.

6.

4. The pelletizing raw material according to any one of claims 1 to 3, characterized in that: The raw materials of the mixture include water, and the added amount of water accounts for 6-8% of the total amount of mineral components.

5. An iron ore cold consolidation pellet, characterized in that: The pellet raw material is the raw material according to any one of claims 1 to 4.

6. The cold-consolidated pellets according to claim 5, characterized in that: The pellets are obtained by pelletizing and pre-calcining the raw material according to any one of claims 1 to 4.

7. The cold-consolidated pellets according to claim 6, characterized in that: The pre-baking temperature is 920±5° C., and the pre-baking time is 10 to 12 minutes.

8. The cold-consolidated pellets according to any one of claims 5 to 7, characterized in that: The cold consolidation strength of the pellets is greater than 2000 N / Pellet.

9. A method for preparing cold-consolidated pellets, characterized in that: include: The pelletizing raw material according to any one of claims 1 to 4 is subjected to a pelletizing treatment to obtain pellets; Alternatively, the pelletizing raw material according to any one of claims 1 to 4 is subjected to a pelletizing treatment to obtain pellets, and the obtained pellets are further pre-calcined.

10. The preparation method according to claim 9, characterized in that: The pelletizing raw materials are pressed and shaped into pellets using a tablet press, and the forming pressure is 55-60MPa; and / or the pre-baking temperature is 920±5°C and the pre-baking time is 10 to 12 minutes; And / or after pelletizing, the obtained pellets are dried and then pre-calcined.

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