阅读说明：本技术 一种冶金球团用改性膨润土及其生产工艺 (Modified bentonite for metallurgical pellets and production process thereof ) 是由 孙云晶 王学林 刘春� 于 2021-08-25 设计创作，主要内容包括：本发明属于膨润土技术领域,具体涉及一种冶金球团用改性膨润土及其生产工艺。生产工艺包括如下步骤：1)将膨润土矿石去除固体杂质,进行混配；2)破碎；3)在破碎后的原矿石中加入碳酸钠和水,搅拌均匀；4)对步骤3)得到的混合料进行再一次破碎,破碎后物料的粒径为3-5mm；5)将步骤4)得到的物料实施场地堆放进行物料的闷放陈化；6)将步骤5)得到的物料晾晒至水分为20-24％；再由旋转窑干燥至物料水分为11-14％；7)根据干燥后的物料的指标决定是否再掺混或调整某种原料的量,同时加入高粘度有机聚合物和轻烧镁；8)将步骤7)得到的混合好的物料进行磨粉；9)将完成磨粉的物料进行包装、入库。(The invention belongs to the technical field of bentonite, and particularly relates to modified bentonite for metallurgical pellets and a production process thereof. The production process comprises the following steps: 1) removing solid impurities from the bentonite ore, and mixing; 2) crushing; 3) adding sodium carbonate and water into the crushed raw ore, and uniformly stirring; 4) crushing the mixture obtained in the step 3) again, wherein the particle size of the crushed material is 3-5 mm; 5) carrying out closed-releasing aging on the materials obtained in the step 4) by stacking in a field; 6) airing the material obtained in the step 5) until the water content is 20-24%; drying the mixture by a rotary kiln until the moisture of the material is 11-14%; 7) determining whether to blend or adjust the amount of a certain raw material according to the index of the dried material, and simultaneously adding a high-viscosity organic polymer and light-burned magnesium; 8) grinding the mixed material obtained in the step 7); 9) and packaging and warehousing the milled materials.)

1. The modified bentonite for the metallurgical pellets is characterized in that the production process comprises the following steps:

1) removing solid impurities from the bentonite ore, and mixing according to a proportion;

2) crushing the mixed raw ore;

3) adding sodium carbonate and water into the crushed raw ore, and uniformly stirring to convert calcium bentonite into sodium bentonite;

4) crushing the mixture obtained in the step 3) again, wherein the particle size of the crushed material is 3-5 mm;

5) carrying out closed-releasing aging on the materials obtained in the step 4) by stacking in a field;

6) airing the material obtained in the step 5) until the water content is 20-24%; drying the mixture by a rotary kiln until the moisture of the material is 11-14%;

7) determining whether to blend or adjust the amount of a certain raw material according to the index of the dried material, and simultaneously adding a high-viscosity organic polymer and light-burned magnesium;

8) grinding the mixed material obtained in the step 7) into powder, wherein the grain size of the ground powder is-80 to-400 meshes;

9) and packaging and warehousing the milled materials.

2. The modified bentonite for metallurgical pellets as claimed in claim 1, wherein in step 1), the indexes of the raw ore are as follows, the blue absorption is not less than 24.0g/100g, the expansion times are not less than 13ml/2g, the colloid value is not less than 400ml/15g, the expansion capacity is not less than 15ml/g, and the water absorption is not less than 400%.

3. The modified bentonite for metallurgical pellets as claimed in claim 2, wherein in the step 2), the crushed particle size is less than 5 cm.

4. The modified bentonite for metallurgical pellets as claimed in claim 3, wherein in step 3), industrial sodium carbonate is added in a mass ratio of 4.0% of the dry mass of the crushed raw ore, and water is added to make the water content of the material between 30% and 34%.

5. The modified bentonite for metallurgical pellets as claimed in claim 4, wherein the aging time in step 5) is 15-30 days.

6. The modified bentonite for metallurgical pellets as claimed in claim 5, wherein in the step 6), the outlet temperature of the combustion chamber of the rotary kiln is controlled within 750-800 ℃.

7. The modified bentonite as claimed in claim 6, wherein in step 7), the high viscosity organic polymer is one or more of CMC, sodium polyacrylate and carboxymethyl starch.

8. The modified bentonite for metallurgical pellets as claimed in claim 7, wherein in the step 7), the dried materials are as follows according to mass ratio: high viscosity organic polymer: light-burned magnesium 97-99%: 0-2%: 1 percent.

9. The modified bentonite for metallurgical pellets as claimed in claim 7 or 8, wherein humic acid is used instead of high viscosity organic polymer.

Technical Field

The invention belongs to the technical field of bentonite, and particularly relates to modified bentonite for metallurgical pellets and a production process thereof.

Background

The pellet binder is used as an important auxiliary material for pellet production, and has important influence on pellet quality and preparation process thereof. Through gradually knowing various properties of the bentonite, the bentonite product is vigorously researched and developed to be used in the production of iron ore pellets, so that the bentonite becomes a main binder for the production of the iron ore pellets.

At present, the pellet binders used in pellet production by steel enterprises are mainly inorganic binders and organic binders.

The inorganic binder is prepared by producing and processing bentonite, and is widely used due to low price, easy obtaining, simple processing procedure, sufficient resources, good balling and anti-explosion performance. The disadvantages are that the addition amount is large during pelletizing, the iron grade of the pellets is reduced, the iron slag amount is large during blast furnace smelting of the pellets, the smelting cost is increased, and the energy consumption and the loss in the production process are large. Causing energy waste.

The organic binder mainly uses high molecular substances as the pellet binder, has the advantages of low addition amount, low impurity content, high pellet iron grade and the like, but is less applied in pellet production because of the defects of difficult addition and mixing, poor pelletizing performance, poor green pellet thermal performance, high production cost and the like.

The existing inorganic binder is shown in figure 1 in the production and processing process, and the processes are as follows:

1. crushing of raw ore

The raw bentonite ore required by the product is mixed with stones (blocks) in blocks and surfaces, so that the raw ore needs to be crushed into small blocks in advance to facilitate grinding, and the stones (blocks) in the raw ore are sorted out during crushing.

2. Airing clothes

In order to smoothly grind raw ores and ensure that the water content of a product is qualified, the raw ores are required to be manually aired to a proper water content degree.

3. Mixing and blending

In order to ensure the product quality, 2-3 kinds of bentonite raw ore are required to be mixed for production, and meanwhile, in the mixing process, industrial sodium carbonate with corresponding quality is added to convert calcium bentonite into sodium bentonite so as to obtain qualified bentonite products.

4. Milling powder

Grinding the mixed semi-finished raw materials to obtain a qualified product with the required particle size.

5. Packaging and warehousing

And packaging and warehousing the qualified bentonite products, and performing identification and prevention.

According to the experiment, the bentonite ores in the Maxi ditch mining area, the Mabei mountain mining area, the four-section beam mining area and the Mupin sub mining area are used as raw materials and are processed by the processing method, and the properties of the processed bentonite are shown in table 1.

TABLE 1

Raw ore	Massachusetts groove	Mabeishan mountain	Four-section beam	Walking stick
					Amount of alkali added (%)	4.0	4.0	4.0	4.0
Amount of blue absorbed (g/100g)	28.0	26.0	22.0	21.0
					Expansion times (ml/2g)	16	12	16	20
Glue price (ml/15g)	420	400	490	470
					Expansion container (ml/g)	18	15	25	20
Water absorption (2h,%)	420	400	450	490

In the production process in the prior art, the key links are mixing and grinding. The control and design of this link also become a disadvantage of the prior art, and the reasons are as follows:

1) whether the performances of the raw materials required for mixing are complementary and the complementary degree;

2) the mixing degree is not uniform;

3) the utilization rate of the industrial sodium carbonate is different.

Disclosure of Invention

Aiming at the advantages and disadvantages of inorganic binder and organic binder used in pellet production, the invention not only solves the problem of large addition amount of inorganic binder, but also improves the iron grade of pellets, improves the performance of pellets and takes into account the advantages of both.

In order to achieve the purpose, the technical scheme of the invention is as follows, the production process of the modified bentonite for the metallurgical pellets comprises the following steps:

1) removing solid impurities from the bentonite ore, and mixing according to a proportion;

2) crushing the mixed raw ore;

3) adding sodium carbonate and water into the crushed raw ore, and uniformly stirring to convert calcium bentonite into sodium bentonite;

4) crushing the mixture obtained in the step 3) again, wherein the particle size of the crushed material is 3-5 mm;

5) carrying out closed-releasing aging on the materials obtained in the step 4) by stacking in a field;

6) airing the material obtained in the step 5) until the water content is 20-24%; drying the mixture by a rotary kiln until the moisture of the material is 11-14%;

7) determining whether to blend or adjust the amount of a certain raw material according to the index of the dried material, and simultaneously adding a high-viscosity organic polymer and light-burned magnesium;

8) grinding the mixed material obtained in the step 7) into powder, wherein the grain size of the ground powder is-80 to-400 meshes;

9) and packaging and warehousing the milled materials.

Preferably, in the step 1), the indexes of the raw ore are that the blue absorption is more than or equal to 24.0g/100g, the expansion time is more than or equal to 13ml/2g, the colloid value is more than or equal to 400ml/15g, the expansion volume is more than or equal to 15ml/g, and the water absorption is more than or equal to 400%.

Preferably, in the modified bentonite for metallurgical pellets, in the step 2), the particle size after crushing is less than 5 cm.

Preferably, in the step 3), industrial sodium carbonate is added according to the mass ratio of 4.0% of the dry mass of the crushed raw ore, and water is added to ensure that the moisture of the material is between 30 and 34%.

Preferably, in the modified bentonite for metallurgical pellets, in the step 5), the time for aging is 15-30 days.

Preferably, in the step 6), the outlet temperature of the combustion chamber of the rotary kiln is controlled to be 750-800 ℃.

Preferably, in the modified bentonite for metallurgical pellets, in step 7), the high-viscosity organic polymer is one or more of CMC, sodium polyacrylate and carboxymethyl starch.

Preferably, in the step 7), the dried material is: high viscosity organic polymer: light-burned magnesium 97-99%: 0-2%: 1 percent.

Preferably, the modified bentonite for the metallurgical pellets adopts humic acid to replace high-viscosity organic polymers. The invention has the beneficial effects that:

1. complete transformation and modification of bentonite are completed, and the utilization rate of industrial sodium carbonate is improved;

2. the bentonite raw ore is subjected to 9 working procedures of mixing operation, so that the mixing effect of raw ore materials is better;

3. the complementarity of the properties of the raw ore is improved;

through mixing, the blue absorption, expansion times, colloidal value, expansion capacity and water absorption index of the product are adjusted to meet the requirements.

4. The product has good quality stability;

the bentonite of the invention can meet the following requirements: the blue absorption is more than or equal to 24.0g/100g, the expansion time is more than or equal to 13ml/2g, the colloidal value is more than or equal to 400ml/15g, the expansion capacity is more than or equal to 15ml/g, and the water absorption is more than or equal to 400%. According to the production process, after the raw ore is mixed, the indexes of the product meet the requirements, and the stability of the product is ensured because the materials are mixed in a plurality of processes and the mixing effect is good.

5. The product has good use effect, and in the actual production, the use effect of the inorganic binder of 1.8-2.5% can be achieved when the addition of the product is 0.8-1.5%, so that the green pellet strength can be obviously improved, the green pellet thermal stability can be improved, the binder proportion can be reduced, the material return rate can be reduced, and the iron grade of the pellet ore can be improved.

6. The invention mainly uses the stirring function of the stirrer to uniformly mix the materials with alkali and water, has not obvious or quick effect on the transformation of the bentonite, can accelerate the transformation of the bentonite if upgraded transformation equipment (such as roller type layering extrusion equipment) is used, and basically does not need subsequent extrusion crushing and material stewing and aging processes. The extruded material can be directly dried.

7. Mixing the dried materials

Can use equipment to carry out the compounding, increase the degree of consistency after the material mixes, avoid the inhomogeneous problem of material that the loader compounding brought.

Drawings

FIG. 1 is a flow chart of the production process of the prior modified bentonite.

FIG. 2 is a flow chart of the production process of the modified bentonite of the invention.

Detailed Description

The bentonite ore selected by the invention is selected from a Maxi ditch mine area, a Mabeishan mine area, a four-section beam mine area and a Mupin mine area.

Example 1

Aiming at the defects of the prior art, the invention improves the production and processing technology of the prior art, and the improved production and processing technology is shown in figure 2. The method comprises the following specific steps:

1. blending of raw ore

3 raw ores (Ma xi ditch: Ma Bei mountain: Munzi) are mixed according to the mass ratio of 40%: 30%: mixing at a ratio of 30%, mixing by a loader or a mixing device, and removing stone blocks and other solid impurities in the raw ore by manual work or a screening device before mixing.

2. Crushing

The method is characterized in that a tooth-type crusher is used for strongly crushing raw ores, meanwhile, a sieve bar with a certain width is arranged at the upper part of the tooth-type crusher and used for removing stone blocks or harder raw ores again, and the particle size of the crushed materials needs to be smaller than 5 cm. The main function is to increase the specific surface area of the bentonite, which is beneficial to the contact of the bentonite and the industrial sodium carbonate.

3. Sodium modification

Adding industrial sodium carbonate and a proper amount of water according to 4.0 percent of the dry mass of the crushed bentonite raw ore, stirring and uniformly mixing in a double-shaft stirrer, and performing primary transformation on the calcium-based soil. The water content of the material is required to be 30-34%. The industrial sodium carbonate acts as a transformation agent to transform the bentonite from calcium-based soil to sodium-based soil, and the water content is kept to be mainly beneficial to the migration of sodium ions in the materials so as to accelerate the transformation of the bentonite.

4. Crushing by extrusion

And extruding and crushing the uniformly stirred mixture again to accelerate the transformation of the bentonite, and controlling the particle size of the extruded and crushed material to be 3-5 mm.

5. Ageing by stewing

And (5) stacking in a field, and finishing the transformation of the bentonite, wherein the aging time is 15-30 days.

6. Drying in the sun, drying

The thoroughly transformed material is firstly aired manually until the moisture content is 20-24%, and then dried by a rotary kiln until the moisture content of the material is 11-14%, or the moisture content of the product is correspondingly controlled according to the requirements of customers. The outlet temperature of the combustion chamber during drying is controlled at 750 ℃ and not more than 800 ℃ at most.

7. Mixing material

The process mainly comprises the steps of determining whether to re-blend or adjust the amount of certain calcium-based soil raw ore after manual airing according to dried material indexes (blue absorption amount, expansion times, colloid value, expansion capacity and water absorption), simultaneously adding CMC and light-burned magnesium, wherein the adding amount of CMC is 2% of the total material mass during mixing, the adding amount of light-burned magnesium is 1% of the total material mass, and blending the materials by a loader until the materials are uniform.

8. Milling powder

The mixed materials are ground into powder, the grinding equipment is a Raymond mill, the particle size of the prepared modified bentonite is-80 meshes to-400 meshes, and the passing rate is 80-98%. In the process of grinding, under the action of strong shearing force generated by strong extrusion and friction of equipment, the high molecular substance is intercalated into the crystal lattice of the bentonite, so that the modification of the bentonite is realized.

9. Packaging and warehousing

And packaging and warehousing products according to the requirements of customers, and implementing identification and prevention.

Example 2

The bentonite ore in one of the ore areas of the Maxi-ditch ore area, the Mabeishan ore area, the four-section beam ore area and the Munzi-sub ore area is modified according to the steps in the example 1, the mass ratio of the bentonite ore, CMC and light burned magnesium is adjusted, and the result is as follows:

1) the results of adding CMC to different raw ores with the controlled 1.0% soft-burned magnesium are shown in tables 2 to 6.

(xi) Ma West ditch raw ore

TABLE 2

② raw ore of Mabeishan mountain

TABLE 3

Third four sections of beam raw ore

TABLE 4

Four crude ore of walking stick

TABLE 5

Example 3

The mixture ratio is Maxigou: mabeishan: pole-40%: 30%: 30 percent of the mixed raw ore is obtained, and 2.0 percent of CMC is supplemented for implementation. After blending production, the product has the following results:

TABLE 6

Example 4

Adjusting the raw ore and the raw ore ratio, wherein the ratio is as follows: mabeishan: four sections of beams are 30%: 40%: 30 percent of the mixed raw ore is obtained, and 1.5 percent of CMC is supplemented. Under the condition of ensuring 1.0 percent of the addition of the light burned magnesium, the product after the production is proportioned has the following results:

TABLE 7

Example 5

Adjusting the raw ore and the raw ore ratio, wherein the ratio is as follows: massachusetts: four sections of beams: 60% of crutch: 20%: 20 percent of the mixed raw ore is obtained, and 0.5 percent of CMC is supplemented. Under the condition of ensuring 1.0 percent of the addition of the light burned magnesium, the product after the production is proportioned has the following results:

TABLE 8

Example 6

Proportioning according to example 1: massachusetts: mabeishan: pole-40%: 30%: the mixed raw ore is obtained by the mixture ratio of 30 percent, different additives are added for testing under the condition of 1.0 percent of fixed light-burned magnesium, and the results are as follows:

TABLE 9

Because the performance difference of each index of the ores produced in different mining areas is large, the quality of a final product is influenced, by adopting the method disclosed by the invention, each raw ore is reasonably proportioned, and the light burned magnesium, high-viscosity organic matters or humic acid are added, so that each index of a bentonite product is improved, and the product quality is stable.

In the selection of raw ores, the ores with white, grey, yellow green and the like appearance are selected, the white (grey) minerals are softer, the water absorption rate is high, the adhesive force is slightly low, the yellow minerals are coarse, the water absorption rate is slightly low, and the adhesive force is high; the light-burned magnesium mainly plays a role in improving the bursting temperature and preventing the pellets from bursting in the product; the addition of CMC can improve the quality of pellet soil, improve the quality of pellets, reduce the proportion of pellet binder and improve the thermal stability of pellets.