Preparation and use method of composite bentonite slurry for pellets

Abstract

The invention discloses a preparation and use method of composite bentonite slurry for pellets, and the preparation and use method comprises the following steps: crushing and screening original bentonite to obtain bentonite powder; the preparation method comprises the following steps: adding bentonite powder into water, and stirring and dispersing to obtain bentonite slurry; sequentially adding a sodium modifying agent and a high-molecular organic modifier into the bentonite slurry, and performing ultrasonic treatment and continuous stirring after each time of adding; and carrying out precipitation polymerization reaction, and filtering to obtain the composite bentonite slurry. The use method comprises the step of directly spraying the composite bentonite slurry on iron ore concentrate to prepare pellets. According to the method, purification, sodium modification and organic modification are integrated, the sodium modification and organic synergistic modification effects of the bentonite slurry are optimized in an ultrasonic mode, the pellets are prepared in a mode of directly spraying the composite bentonite slurry, the pelletizing property and the pellet strength of bentonite are improved, the dewatering cost of the bentonite slurry is saved, and the method is suitable for industrial production. And a bentonite and iron ore concentrate mixing process can be omitted, so that the production time is greatly saved.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgical pelletizing, and in particular to a method for preparing and using composite bentonite slurry for pelletizing. Background Art

[0002] Bentonite is widely used as a pellet binder in the field of metallurgical pellets. Montmorillonite, as the main component of bentonite, is a 2:1 layered silicate clay mineral, whose unit crystal layer consists of two layers of silicon dioxide tetrahedrons sandwiching one layer of aluminum oxide octahedron. 3+ and Si 4+ It is easy to be replaced by low-valent cations. Montmorillonite sheets usually have permanent electronegativity. In order to achieve charge balance, montmorillonite interlayers usually contain a large number of exchange cations (Ca 2+ , K + 、Na + , Li + etc.), Ca 2+ The binding energy of Ca 2+ It is easier to adsorb between montmorillonite layers. Therefore, naturally formed bentonite is mainly calcium-based bentonite, but the performance of natural calcium-based bentonite is generally poor. With the decreasing reserves of high-quality natural bentonite resources, it is urgent to find a way to improve the performance of natural bentonite.

[0003] If composite bentonite is made of sodium agent, organic matter + bentonite, not only can the amount of bentonite used be reduced, but the high-performance composite bentonite can also improve the spheroidization and pellet strength of the material. It itself will not increase the cost of pelletized ore, and the economic and social benefits are very obvious.

[0004] At present, there are three main bentonite composite processes: dry process, semi-dry process and wet process, among which the wet process has the best treatment effect. However, the bentonite wet process requires the addition of a large amount of water, and the bentonite and the reagent must be blended and fully dispersed in the water. The resulting composite bentonite also needs to be dried at high temperature, which consumes a lot of energy and takes a long time. Summary of the invention

[0005] In order to overcome the shortcomings of the above-mentioned technology, the purpose of the present invention is to provide a method for preparing and using a composite bentonite slurry for pelletizing, which can effectively improve the performance of bentonite, thereby improving the balling property and pellet strength.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing composite bentonite slurry for pelletizing comprises the following steps:

[0008] 1) crushing and sieving bentonite raw soil to obtain bentonite powder;

[0009] 2) adding the bentonite powder into water and stirring to fully disperse the bentonite powder in the water to obtain a bentonite slurry;

[0010] 3) adding a sodium-forming agent to the bentonite slurry, subjecting it to ultrasonic treatment and continuous stirring to fully form sodium;

[0011] 4) adding a high molecular weight organic modifier to the sodium-treated bentonite slurry, subjecting it to ultrasonic treatment and continuously stirring;

[0012] 5) The bentonite slurry treated with the polymer organic modifier is subjected to precipitation polymerization reaction for 1 to 3 hours. After the reaction is completed, the filter residue is removed by filtering to obtain a composite bentonite slurry.

[0013] Preferably, in step 1), the crushing includes coarse crushing, fine crushing and fine grinding processes; wherein the coarse crushing uses a jaw crusher and the fine crushing uses a roll crusher; the particle size of the bentonite powder is below -0.074 mm.

[0014] Preferably, in step 2), the mass percentage of bentonite in the bentonite slurry is 20% to 40%; and the pH of the bentonite slurry is 7.5 to 8.5.

[0015] Preferably, in the step 2), the mass percentage of bentonite in the bentonite slurry is 30%, and the pH value of the bentonite slurry is 8.

[0016] Preferably, in step 3), the sodiumizing agent is one or more of sodium pyrophosphate, sodium hexametaphosphate and sodium carbonate; and the amount of the sodiumizing agent is 1.5-2.0% of the mass of the bentonite powder.

[0017] Preferably, in step 4), the high molecular organic agent is CMC and / or humic acid; the amount of the high molecular organic agent is 0.5-1.0% of the mass of the bentonite powder.

[0018] Preferably, in steps 3) and 4), the ultrasonic power is 250 W, the agitator speed is 200 r / min, and the ultrasonic treatment time is 5 to 20 min.

[0019] Preferably, in step 5), the reaction temperature is 80° C. and the reaction time is 2 h.

[0020] A method for using composite bentonite slurry for pelletizing comprises spraying the composite bentonite slurry directly on iron concentrate to prepare pellets; the composite bentonite slurry is prepared by the above-mentioned preparation method.

[0021] Preferably, the spraying rate of the composite bentonite slurry is calculated by the following formula: 浆液 =M 铁精矿×I×7 / 3; where M 浆液 is the spraying rate of composite bentonite slurry, in t / h; M 铁精矿 is the iron ore concentrate feeding rate, in t / h; I is the original bentonite ratio, in %.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The composite bentonite slurry preparation method of the present invention integrates purification, sodiumization and organic modification, optimizes the sodiumization modification and organic synergistic modification effects of the bentonite slurry by ultrasound, and directly prepares pellets by spraying the composite bentonite slurry, which not only effectively improves the spheroidization and pellet strength of the bentonite, saves the cost of dehydrating the bentonite slurry, but also eliminates the process of mixing bentonite and iron concentrate, greatly saving production time.

[0024] The present invention uses an ultrasonic instrument to process a composite bentonite slurry. The ultrasonic treatment can peel off the interlayer structure of the bentonite and expand the distance between the layers, thereby improving the adsorption capacity of the bentonite to a sodium agent and an organic agent, realizing sodium modification and coordinated organic modification to prepare an excellent bentonite slurry. Finally, the composite bentonite slurry is sprayed and added into a pelletizing process, which can effectively improve the balling property and pellet strength of the material, reduce production costs, and improve production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The present invention is a schematic flow diagram of a method for preparing and using a composite bentonite slurry for pelletizing. DETAILED DESCRIPTION

[0026] In order to better explain the present invention, the main contents of the present invention are further explained below in conjunction with the drawings and specific embodiments, but the contents of the present invention are not limited to the following embodiments.

[0027] like Figure 1 As shown, the present invention provides a method for preparing a composite bentonite slurry for pelletizing, comprising the following steps:

[0028] 1) Take the bentonite raw soil, crush it and screen it to obtain bentonite powder; crushing includes coarse crushing, fine crushing and fine grinding processes; among them, the coarse crushing uses a jaw crusher, and the fine crushing uses a roller crusher; the particle size of the bentonite powder is below -0.074mm. Crushing the bentonite can improve the dispersion of the bentonite in water, which is conducive to the full dispersion of the bentonite in water.

[0029] 2) Adding the bentonite powder into water and stirring to fully disperse the bentonite powder in the water to obtain bentonite slurry; the mass percentage of bentonite in the bentonite slurry is 20% to 40%; and the pH of the bentonite slurry is 7.5 to 8.5.

[0030] 3) adding a sodiumizing agent to the bentonite slurry, subjecting it to ultrasonic treatment and continuous stirring for 5 to 20 minutes to fully sodiumize it; the sodiumizing agent is one or more of sodium pyrophosphate, sodium hexametaphosphate and sodium carbonate; and the amount of the sodiumizing agent is 1.5 to 2.0% of the mass of the bentonite powder.

[0031] 4) Adding a high molecular weight organic modifier to the sodium treated bentonite slurry, ultrasonically treating and stirring the mixture for 5 to 20 minutes; the high molecular weight organic modifier is CMC and / or humic acid, and the amount of the high molecular weight organic modifier is 0.5 to 1.0% of the mass of the bentonite powder.

[0032] In step 3) and step 4), the ultrasonic power is 250W and the agitator speed is 200r / min.

[0033] 5) subjecting the bentonite slurry modified by the macromolecular organic modifier to a precipitation polymerization reaction for 1 to 3 hours. After the reaction is completed, filtering and removing the filter residue to obtain a composite bentonite slurry.

[0034] The 2h water absorption rate of the above-mentioned bentonite raw soil is 150-300%, the swelling capacity is <10ml / g, and the blue absorption amount is >15g / 100g.

[0035] The present invention also provides a method for using the composite bentonite slurry for pelletizing prepared by the above preparation method, wherein the composite bentonite slurry is directly sprayed on the iron ore concentrate to prepare pellets. The spraying rate is calculated by the following formula: M 浆液 =M 铁精矿 ×I×7 / 3; where M 浆液 is the spraying rate of composite bentonite slurry, in t / h; M 铁精矿 is the iron ore concentrate feeding rate, in t / h; I is the original bentonite ratio, in %.

[0036] The present invention is further described below by way of Examples 1 and 2. Examples 1 and 2 are all prepared by the above-mentioned preparation method, and the difference lies in the different process parameters.

[0037] Example 1

[0038] The parameters of the preparation method of the composite bentonite slurry for pelletizing in this embodiment are as follows:

[0039] In step 1), the bentonite is calcium-based bentonite, and its chemical composition is shown in Table 1; the physical properties are as follows: 2h water absorption is 264.3%, swelling capacity is 8.2ml / g, blue absorption is 18.79g / 100g, and moisture content is 4.3%.

[0040] Table 1 Main chemical components of bentonite raw soil / %

[0041] chemical composition TFe <![CDATA[SiO2]]> CaO MgO <![CDATA[Al2O3]]> <![CDATA[K2O]]> <![CDATA[Na2O]]> LOI content 3.18 62.40 1.25 1.06 17.82 1.01 2.26 12.32

[0042] In step 2), the solid-liquid mass ratio is 3:7; the pH of the bentonite slurry is controlled at 8.

[0043] In step 3), sodium pyrophosphate is used as the sodiumizing agent in an amount of 1.5% of the weight of the bentonite; and ultrasonic treatment is performed for 10 minutes.

[0044] In step 4), the high molecular organic modifier is CMC, and the amount used is 0.5% of the weight of bentonite; ultrasonic treatment is performed for 10 minutes.

[0045] In step 5), the polymerization reaction temperature is 80° C. and the polymerization reaction time is 2 h.

[0046] The composite bentonite slurry prepared in this example is used for direct spraying to prepare pellets. During the pellet preparation process, the iron ore feed rate M 铁精矿 The original bentonite ratio I is 1.2%. The slurry spraying rate M is calculated from the spraying rate. 浆液 The inclination angle and speed of the pelletizing disk are 47° and 25r / min, the pelletizing time is 12min, and the bentonite ratio is 1.0%.

[0047] Compared with the original calcium-based bentonite without sodium treatment and modification, the green ball drop strength, compressive strength and burst temperature increased from 2.3 times / 0.5m, 8N / piece and 425℃ to 5.1 times / 0.5m, 17N / piece and 513℃ respectively. The green ball compressive strength, drop strength and burst temperature were significantly improved.

[0048] Example 2

[0049] The parameters of the preparation method of the composite bentonite slurry for pelletizing in this embodiment are as follows:

[0050] In step 1), the bentonite is calcium-based bentonite, and its chemical composition is shown in Table 2; the physical properties are as follows: 2h water absorption is 161.1%, swelling capacity is 3.1ml / g, blue absorption is 21.80g / 100g, and moisture content is 7.46%.

[0051] Table 1 Main chemical components of bentonite raw soil / %

[0052] chemical composition <![CDATA[Fe2O3]]> <![CDATA[SiO2]]> CaO MgO <![CDATA[Al2O3]]> <![CDATA[K2O]]> <![CDATA[Na2O]]> P S LOI content 5.32 60.71 1.48 2.01 15.65 1.85 0.84 0.055 0.051 12.32

[0053] In step 2), the solid-liquid mass ratio is 3:7; the pH of the bentonite slurry is controlled at 8.

[0054] In step 3), sodium carbonate is used as the sodiumizing agent in an amount of 2.0% by weight of the bentonite; ultrasonic treatment is performed for 5 minutes.

[0055] In step 4), the high molecular organic modifier is humic acid, and the amount used is 1.0% of the weight of bentonite; ultrasonic treatment is performed for 5 minutes.

[0056] In step 5), the polymerization reaction temperature is 80° C. and the polymerization reaction time is 2 h.

[0057] The composite bentonite slurry prepared in this example is used for direct spraying to prepare pellets. During the pellet preparation process, the iron ore feed rate M 铁精矿 The original bentonite ratio I is 1.2%. The slurry spraying rate M is calculated from the spraying rate. 浆液 The inclination angle and speed of the pelletizing disk are 47° and 25r / min, the pelletizing time is 12min, and the bentonite ratio is 1.0%.

[0058] Compared with the original calcium-based bentonite without sodiumization and organic modification, the green ball drop strength, compressive strength and burst temperature increased from 2.3 times / 0.5m, 8N / piece and 425℃ to 4.8 times / 0.5m, 19N / piece and 557℃ respectively. The green ball compressive strength, drop strength and burst temperature were significantly improved.

[0059] In summary, the composite bentonite slurry preparation method of the present invention integrates purification, sodiumization and organic modification, optimizes the sodiumization modification and organic synergistic modification effect of the bentonite slurry by ultrasound, and directly prepares pellets by spraying the composite bentonite slurry, which not only improves the spheroidization and pellet strength of the bentonite, saves the cost of dehydrating the bentonite slurry, but also removes the process of mixing bentonite with iron concentrate, greatly saving production time. The bentonite slurry of the present invention is used for pellet preparation, which can significantly improve the compressive strength, drop strength and burst temperature of the green ball, and has the advantages of low cost and high production efficiency.

Claims

1. A method for preparing composite bentonite slurry for pelletizing, characterized in that: The following steps are involved: 1) crushing and sieving bentonite raw soil to obtain bentonite powder; 2) adding the bentonite powder into water and stirring to fully disperse the bentonite powder in the water to obtain a bentonite slurry; 3) adding a sodium-forming agent to the bentonite slurry, subjecting it to ultrasonic treatment and continuous stirring to fully form sodium; 4) adding a high molecular weight organic modifier to the sodium-treated bentonite slurry, subjecting it to ultrasonic treatment and continuously stirring; 5) The bentonite slurry treated with the polymer organic modifier is subjected to precipitation polymerization reaction for 1 to 3 hours. After the reaction is completed, the filter residue is removed by filtering to obtain a composite bentonite slurry.

2. The preparation method according to claim 1, characterized in that: In the step 1), the crushing includes coarse crushing, fine crushing and fine grinding processes; wherein the coarse crushing uses a jaw crusher and the fine crushing uses a roll crusher; the particle size of the bentonite powder is below -0.074 mm.

3. The preparation method according to claim 1, characterized in that: In the step 2), the mass percentage of bentonite in the bentonite slurry is 20% to 40%; and the pH of the bentonite slurry is 7.5 to 8.

5.

4. The preparation method according to claim 1, characterized in that: In the step 2), the mass percentage of bentonite in the bentonite slurry is 30%, and the pH value of the bentonite slurry is 8.

5. The preparation method according to claim 1, characterized in that: In the step 3), the sodiumizing agent is one or more of sodium pyrophosphate, sodium hexametaphosphate and sodium carbonate; the amount of the sodiumizing agent is 1.5-2.0% of the mass of the bentonite powder.

6. The preparation method according to claim 1, characterized in that: In the step 4), the high molecular organic agent is CMC and / or humic acid; the amount of the high molecular organic agent is 0.5-1.0% of the mass of the bentonite powder.

7. The preparation method according to claim 1, characterized in that: In the steps 3) and 4), the ultrasonic power is 250 W, the agitator speed is 200 r / min, and the ultrasonic treatment time is 5 to 20 min.

8. The preparation method according to claim 1, characterized in that: In the step 5), the reaction temperature is 80° C. and the reaction time is 2 h.

9. A method for using a composite bentonite slurry for pelletizing, characterized in that: The method comprises spraying the composite bentonite slurry directly on the iron concentrate to prepare pellets; the composite bentonite slurry is prepared by the preparation method according to any one of claims 1 to 8.

10. The method of use according to claim 9, characterized in that: The spraying rate of the composite bentonite slurry is calculated by the following formula: 浆液 =M 铁精矿 ×I×7 / 3; where M 浆液 is the spraying rate of composite bentonite slurry, in t / h; M 铁精矿 is the iron ore concentrate feeding rate, in t / h; I is the original bentonite ratio, in %.

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