Iron-rich low-silicon composite binder for iron ore pellets and preparation method of iron-rich low-silicon composite binder

Abstract

The invention belongs to the field of metallurgy, and particularly relates to an iron-rich low-silicon composite binder for iron ore pellets and a preparation method of the iron-rich low-silicon composite binder. According to the specific preparation method, raw materials are dried, ground and sieved to obtain the composite binder, and the binder improves the binding effect of concentrate powder particles. The additive is prepared at normal temperature, so that the consolidation of the pellets is not influenced in the oxidizing roasting stage of the pellets. In the production process of the iron ore pellets, a large number of binders need to be used, the raw materials for preparing the binders are cheap and easy to obtain, the production cost is greatly reduced, and meanwhile when the binders are used for producing the iron ore pellets, the performance of the pellets can be obviously improved.

Description

Technical Field

[0001] The invention belongs to the field of metallurgy, and in particular relates to an iron-rich, low-silicon composite binder for iron ore pellets and a preparation method thereof. Background Art

[0002] With the expansion of my country's steel production capacity, the demand for pellets, one of the raw materials for iron smelting, is also increasing. Binders are an important component of the raw materials for pellet production. The binder is mixed with iron ore concentrate powder, and then the disc ball method is used to prepare green balls. Pellets are obtained after drying and oxidation roasting. Adding binders in the preparation process of green balls will play a role in regulating moisture and stabilizing the growth of green balls. At the same time, the addition of binders will make the iron ore particles bond more tightly and improve the strength of iron ore pellets. Most pelletizing plants in my country use bentonite as a binder, but the addition of bentonite will introduce harmful impurities into iron ore pellets. Nowadays, the resources of high-quality bentonite are decreasing. In order to meet the new economic model and improve resource utilization, it is urgent to find new binder materials to eliminate the adverse effects of bentonite quality deterioration on the performance of iron ore pellets.

[0003] At present, binders can be mainly divided into: inorganic binders, organic binders and composite binders. Common inorganic binders include bentonite, diatomaceous earth, cement, water glass, bentonite, quicklime, borate and fly ash, etc.; organic binders include dextrin, starch, sodium carboxymethyl cellulose, polyacrylamide, polyvinyl alcohol, etc.; composite binders are made by modifying inorganic and organic binders in a certain proportion. Organic binders can improve the strength of raw balls, with small dosage and low residue, but they are expensive and have poor thermal stability, which is not conducive to large-scale production and use. Summary of the invention

[0004] In view of the problems existing in the background technology, the present invention provides an iron-rich, low-silicon composite binder for iron ore pellets and a preparation method thereof. The composite binder is prepared by modifying bentonite and an organic binder in a certain proportion.

[0005] This is achieved through the following technical solutions: An iron-rich, low-silicon composite binder for iron ore pellets and a preparation method thereof. The composite binder is composed of, by weight percentage, 65% to 95% dry red mud powder, 0% to 5% magnesium powder, 1% to 6% binder, and 1% to 10% bentonite.

[0006] Preferably, in terms of weight percentage, the portion of the dry red mud powder with a particle size less than 200 mesh is ≥ 95%, and the water content is ≤ 3%.

[0007] Preferably, the binder is hydroxymethyl cellulose.

[0008] Preferably, the iron-rich and low-silicon composite binder for iron ore pellets and the preparation method thereof comprise the following steps: (1) drying the red mud to obtain dry red mud; (2) Mix dry red mud, magnesium powder, hydroxymethyl cellulose and bentonite in proportion and pour into a ball mill. Grind for 48 to 64 hours at a ball: material ratio of 1:1. (3) The ground raw materials are sieved to obtain a composite adhesive.

[0009] Preferably, the drying condition in step (1) is drying at 120° C. for 1 to 2 hours.

[0010] Preferably, a 200-mesh sieve is used for sieving in step (2).

[0011] Further preferably, the main component contents of the prepared composite binder are, by weight percentage, TFe 30%-47%, TiO 2 2%-8%, SiO 2 2%-17%, and Al 2 O 3 7%-19%.

[0012] Compared with the prior art, the present invention has the following technical advantages: The present invention obtains a composite binder by compounding low-quality bentonite with an organic binder, thereby improving the binding effect of concentrate powder particles. The binder is prepared at room temperature and will not affect the consolidation of the pellets during the oxidation roasting stage of the pellets. A large amount of binder is required in the production process of the pellets. The raw materials for preparing the binder of the present invention are cheap and easy to obtain, which greatly reduces the production cost.

[0013] At the same time, when the binder is used in the production of iron ore pellets, the performance of the pellets is improved. In the present invention, the iron ore pellets prepared by using a ratio of 79% dry red mud powder, 5% magnesium powder, 6% hydroxymethyl cellulose, and 10% bentonite as a binder have a green ball drop strength of 16.1 times and a green ball compressive strength of 16.8 N·P. -1 , burst at 601℃, the compressive strength of the calcined ball is 3265 N·P -1 The binder strengthens the falling strength of the green ball by enhancing the hydrophilicity, capillary force and viscosity of the particles. When drying, a small amount of pores are formed on the surface, which is conducive to the discharge of moisture in the ball and increases the bursting temperature of the green ball. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a flow chart for the preparation of an iron-rich, low-silicon composite binder for iron ore pellets. DETAILED DESCRIPTION

[0015] The following embodiments of the technical solution of the present invention are described in detail in conjunction with the embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and cannot be used to limit the protection scope of the present invention.

[0016] It should be noted that the experimental methods used in the implementation examples are all conventional methods unless otherwise specified; the materials, reagents, etc. used, unless otherwise specified, can be obtained from commercial channels.

[0017] In the present invention, unless otherwise specified, all "parts" and percentages (%) refer to percentages by weight.

[0018] In the present invention, unless otherwise specified, the sum of all percentages in all compositions is 100%.

[0019] In the present invention, unless otherwise specified, the numerical range "a-b" represents an abbreviation of any real number combination between a-b, where a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations.

[0020] In the present invention, unless otherwise specified, all embodiments and preferred embodiments mentioned herein can be combined with each other to form a new technical solution.

[0021] In the present invention, unless otherwise specified, all the steps mentioned herein may be performed sequentially or randomly, but are preferably performed sequentially; for example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially; for example, the method may further include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0022] In the present invention, unless otherwise specified, the specific numerical values ​​and specific substances in the embodiments of the present invention may be combined with other features of the description part of the present invention; for example, if the specification mentions that the reaction temperature is 10~100°C, and the embodiment mentions that the reaction temperature is 20°C, then it can be considered that the present invention has specifically disclosed the range of 10~20°C, or the range of 20~100°C, and this range can be combined with other features of the description part to form a new technical solution. Example

[0023] (1) drying the red mud at 120° C. for 1 hour to obtain dry red mud; (2) 5 kg of dry red mud, 0.32 kg of magnesium powder, 0.38 kg of hydroxymethyl cellulose and 0.63 kg of bentonite were mixed and poured into a ball mill. The mixture was ground for 64 hours at a ratio of 1:1 between ball and material. (3) The ground raw materials are passed through a 200-mesh sieve to obtain a composite adhesive. Example

[0024] (1) drying the red mud at 120° C. for 2 hours to obtain dry red mud; (2) 5 kg of dry red mud, 0.29 kg of magnesium powder, 0.29 kg of hydroxymethyl cellulose and 0.29 kg of bentonite were mixed and poured into a ball mill. The mixture was ground for 50 hours at a ratio of 1:1 between ball and material. (3) The ground raw materials are passed through a 200-mesh sieve to obtain a composite adhesive. Example

[0025] (1) drying the red mud at 120° C. for 1 hour to obtain dry red mud; (2) 5 kg of dry red mud, 0.06 kg of magnesium powder, 0.11 kg of hydroxymethyl cellulose and 0.39 kg of bentonite were mixed and poured into a ball mill. The mixture was ground for 54 hours at a ratio of 1:1 between ball and material. (3) The ground raw materials are passed through a 200-mesh sieve to obtain a composite adhesive. Example

[0026] (1) drying the red mud at 120° C. for 2 hours to obtain dry red mud; (2) 5 kg of dry red mud, 0.11 kg of hydroxymethyl cellulose and 0.16 kg of bentonite were mixed and poured into a ball mill. The mixture was ground for 64 hours at a ratio of 1:1 between ball and material. (3) The ground raw materials are passed through a 200-mesh filter to obtain a composite adhesive. Example

[0027] (1) drying the red mud at 120° C. for 2 hours to obtain dry red mud; (2) 5 kg of dry red mud, 0.11 kg of magnesium powder, 0.23 kg of hydroxymethyl cellulose and 0.34 kg of bentonite were mixed and poured into a ball mill. The mixture was ground for 48 hours at a ratio of 1:1 between ball and material. (3) The ground raw materials are passed through a 200-mesh sieve to obtain a composite adhesive.

[0028] Pelletizing test (1) Pour the raw materials for preparing iron ore pellets and the binder (prepared in Examples 1 to 5) into a ball mill and grind for 48 hours at a ratio of 1:1 between balls and materials; (2) Pass the ground raw materials through a 200-mesh sieve; (3) Pour the sieved material into the disc ball making machine, adjust the speed of the disc ball making machine to 25r / min, and form raw balls as the material rolls and drips; (4) drying the prepared green pellets at 100° C. for 24 hours; (5) The dried green pellets were placed in a horizontal tube furnace, preheated at 850°C for 30 minutes, then roasted at 1250°C for 1 hour, and taken out and cooled to room temperature to obtain iron ore pellets. The composite binder prepared in each embodiment corresponds to one type of iron ore pellet, and the five iron ore pellets prepared are named a, b, c, d, and e respectively.

[0029] Pellet performance test Iron ore green ball compressive strength test. According to YB / T4848-2020 "Physical Test Method for Roasted Green Balls", each green ball is placed on the green ball compressive strength tester and pressurized until it breaks. The average value of the maximum force applied to 20 green ball samples is taken as the compressive strength of the green ball.

[0030] (2) Iron ore green ball drop strength test. According to YB / T4848-2020 "Physical Test Methods for Roasted Green Balls", each green ball is repeatedly dropped from a height of 500 mm onto a 10 mm thick steel plate until it breaks. The average of the number of times that 20 green balls do not break is taken as the green ball drop strength.

[0031] (3) Detection of the bursting temperature of iron ore green balls. According to YB / T4848-2020 "Physical Test Methods for Roasted Green Balls", under the conditions of fixed flow rate and variable temperature, the green ball samples (20 balls per group) are continuously replaced until the number of broken balls in this group of samples accounts for 10% of the total number. The green ball bursting temperature is recorded as the temperature.

[0032] (4) Compressive strength test of iron ore pellets. According to GB / T14201-93 "Determination of compressive strength of iron ore pellets", each roasted ball is placed on a compressive strength tester and pressurized until it breaks. The average value of the maximum force applied to 20 roasted ball samples is taken as the compressive strength of the roasted ball.

[0033] The test results are shown in Table 1 Table 1

[0034] The experimental results show that the iron ore pellets prepared with a ratio of 79% dry red mud powder, 5% magnesium powder, 6% hydroxymethyl cellulose and 10% bentonite as binders have a green ball drop strength of 16.1 times and a green ball compressive strength of 16.8N·P. -1 , burst at 601℃, the compressive strength of the calcined ball is 3265 N·P -1 The comprehensive performance is the best, and all indicators of pellets meet the production requirements.

[0035] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. An iron-rich, low-silicon composite binder for iron ore pellets and a preparation method thereof. The composite binder comprises, by weight percentage, 65% to 95% dry red mud powder, 0% to 5% magnesium powder, 1% to 6% binder, and 1% to 10% bentonite.

2. The iron-rich, low-silicon composite binder for iron ore pellets and its preparation method according to claim 1, characterized in that: Calculated by weight percentage, the portion of the dry red mud powder with a particle size less than 200 meshes is ≥ 95%, and the water content is ≤ 3%.

3. The iron-rich, low-silicon composite binder for iron ore pellets and the preparation method thereof according to claim 1, characterized in that: The binder is hydroxymethyl cellulose.

4. The iron-rich, low-silicon composite binder for iron ore pellets and its preparation method according to claims 1 to 3, characterized in that: The following steps are involved: (1) drying the red mud to obtain dry red mud; (2) Mix dry red mud, magnesium powder, hydroxymethyl cellulose and bentonite in proportion and pour into a ball mill, grind for 48 to 64 hours under the condition of ball: material = 1:1; (3) The ground raw materials are sieved to obtain a composite adhesive.

5. The iron-rich, low-silicon composite binder for iron ore pellets and its preparation method according to claim 4, characterized in that: The drying condition in step (1) is drying at 120° C. for 1 to 2 hours.

6. The iron-rich, low-silicon composite binder for iron ore pellets and the preparation method thereof according to claim 4, characterized in that: In step (2), a 200-mesh sieve is used for sieving.

7. The iron-rich, low-silicon composite binder for iron ore pellets and the preparation method thereof according to claims 1 to 6, characterized in that: Calculated by weight percentage, the main components of the prepared composite adhesive are: TFe 30%-47%, TiO2 2%-8%, SiO2 2%-17%, and Al2O3 7%-19%.

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