Method for improving sinter quality by adding bentonite

Abstract

The invention discloses a method for improving the quality of sintered ore by adding bentonite, which comprises the following steps: (1) calculating the proportion of iron-containing raw materials used for sintering, flux mainly comprising quick lime, solid fuel and bentonite according to the target components of the sintered ore, and adding 0-0.5% by weight of bentonite; (2) cutting out the iron-containing raw material, the flux, the solid fuel and the bentonite according to the calculated ratio from the batching tank, conveying to a mixing area, mixing, adding water, uniformly mixing, and bonding the mixture into small balls or large particles; and (3) the bonded small balls or large particles are conveyed to a sintering pallet to be distributed to a sintering machine, and air draft sintering is carried out. According to the method, based on the current production situation that the particle size of fine ore used for producing the sinter is reduced, the negative pressure of the sintering procedure is increased, the layer thickness is reduced and solid fuel consumption is high, the sintering granulation and pelletizing effects are improved by adding bentonite, the air permeability of a mixture is improved, thick material layer sintering is achieved, the produced sinter is excellent in metallurgical performance, the yield is increased, and the production cost is reduced. The unit consumption of solid fuel and the sintering ton cost are reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sinter production, in particular to a method for improving sinter quality by adding bentonite. BACKGROUND

[0002] In recent years, the quality of market sinter ore has gradually deteriorated, and the particle size of the ore has shown a downward trend. However, with the demand for increasing the production capacity of the sintering process, reducing the layer thickness is a common measure to ensure production, but it leads to an increasing trend of sinter return ore, resulting in a decrease in the comprehensive yield of sinter. The sinter return ore needs to be returned to the sintering process to participate in ore matching and the entire sintering process, which not only leads to an increase in production cost, but also causes a significant deterioration of energy consumption in the sintering process, which is not conducive to low-carbon environmental protection.

[0003] In order to improve the quality of sinter and increase the comprehensive yield (yield), under the condition of thick material layer sintering at the present stage, the use amount of quicklime is increased to improve the granulation effect, but due to the limited space for increasing the sinter basicity and the high price of quicklime, the effect of improving the quality of sinter after increasing the quicklime is not very obvious, and the sinter return ore does not show a significant decrease.

[0004] In view of the good balling effect of bentonite used in the pelletizing process, as well as its strong water absorption and good bonding effect, the present application innovatively adds bentonite to the sintering material to improve the sintering granulation effect, so as to improve the material layer permeability and sintering effect, thereby improving the quality and economy of sinter, optimizing the energy consumption of the sintering process, reducing the production cost and carbon emission of the sintering process, and helping low-carbon metallurgy. SUMMARY

[0005] The present application aims to overcome the shortcomings of the prior art and provides a method for improving the quality of sinter by adding bentonite. By adding a certain proportion of bentonite to the sintering raw material during the sintering batching process, the bentonite is fully mixed with the iron-containing raw material, flux and solid fuel to strengthen the granulation and balling effect.

[0006] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows: A method for improving the quality of sinter by adding bentonite, the method comprising the following steps: Step 1) According to the target composition of the sinter, the iron-containing raw material, flux mainly composed of quicklime, solid fuel and bentonite used in sintering are proportioned and calculated, and 0~0.5% of bentonite by weight is added; Step 2) The iron-containing raw material, flux, solid fuel and bentonite proportioned in step 1) are cut out from the batching bin and sent to the mixing area for mixing, and then water is added for uniform mixing, and the mixed material is bonded into particles; Step 3) The particles bonded in step 2) are sent to the sintering trolley for distribution to the sintering machine for air sintering.

[0007] Further, the main component of the bentonite is montmorillonite and a mixture containing montmorillonite, and the silicon content of the comprehensive component is 40% to 75%, and the aluminum content is 10% to 25%.

[0008] Further, in the step 2), the bentonite is cut out by a screw feeder or a disc feeder at a small flow rate, and is sent to a mixing area to be mixed with other sintering raw materials uniformly.

[0009] Further, in the step 2), the mixing area includes a mixing process and a second mixing process.

[0010] Further, in the step 2), the average particle size of the mixed material bonded into particles is greater than 2.5 mm.

[0011] The application is to use bentonite as a binder to replace part of the quicklime, based on the market sintering fine ore particle size showing a downward trend, the cost performance of the fine powder is rising, the fine powder is added in the sintering process, causing the average particle size of the mixed material to further decrease, and the particle size of the mixed material is increased by adding a certain proportion of bentonite to strengthen the granulation and balling. The mixed raw materials are distributed to the sintering machine, the process parameters are properly adjusted, the operation system is stabilized, and the layer thickness is gradually increased to improve the sinter strength, metallurgical properties and solid fuel consumption. After adding bentonite, the average particle size of the sintered ore product increases by 1 to 5 mm, and the yield increases by ≥1%. After adding bentonite, due to the good water absorption of bentonite, 1 to 5 t / h of water is appropriately added in the sintering mixing process and the second mixing process according to the actual mixing effect to strengthen the balling and granulation effect. The addition of bentonite in the application increases the ratio by 0.1%, the silicon content of the sintered ore increases by 0.05%, and when the sintering alkalinity is controlled to be ≥1.8, the iron grade decreases by about 0.1% to 0.15%. In the sintering burden calculation of the application, the iron-containing raw materials represent various ore fines on the market, such as limonite, hematite, magnetite, etc., and the flux represents the raw materials required in the sintering process, such as quicklime, limestone, dolomite, etc. for adjusting the sintering alkalinity, magnesium oxide, etc. indicators, wherein: quicklime represents a flux with a calcium oxide (CaO) content of ≥70%, limestone represents a flux with a calcium oxide (CaO) content of 40% to 60%, and dolomite represents a flux with a magnesium oxide (MgO) content of 15% to 30% and a calcium oxide (CaO) content of 20% to 40%.

[0012] The beneficial effects of the present application are: the method can effectively improve the permeability of the sintering material layer, thereby improving the sinter quality, and the effect on the fine particle size sintering process is remarkable. When the particle size of the sintering raw material is fine, due to the limitation of the air draft capacity, the negative pressure of the flue gas is high, and the machine speed is increased to pursue the yield, which easily leads to the reduction of liquid phase bonding effect, the decrease of sinter strength, the deterioration of sinter quality, the increase of sinter return fines, the recycling of sintering process, the increase of sintering energy consumption, which is not conducive to the energy saving and consumption reduction target, and the increase of production cost. At this time, the use of bentonite for strengthening granulation and balling can effectively improve the permeability of the material layer and improve the sinter quality. The method of the present application is also one of the effective methods for further solving the technical problem of improving the permeability of the sintering material layer. In addition, through the present application, the high cost performance fine particle size ore powder resource for sintering can be further expanded, the sintering ore variety can be enriched, and the sintering cost competitiveness can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 is a sintering cup experiment two mixed sample graph of the embodiment of the present application without adding bentonite; Figure 2 is a sintering cup experiment two mixed sample graph of the embodiment of the present application adding 0.2% bentonite. DETAILED DESCRIPTION

[0014] The present application will be further described in detail below in combination with the embodiments.

[0015] In the following examples, the technical parameters or technical index results described should not be considered in isolation, and each iron-containing raw material and flux are applied in different embodiments. The types and components of the flux in the following cases are only examples and should not be considered to represent only the material of the component.

[0016] The existing method for strengthening the granule mainly improves the effect of strengthening granulation and balling by continuously increasing the proportion of quicklime, and the adjustment measure is single, which has three shortcomings: (1) With the gradual increase of the proportion of quicklime, the effect of improving the sinter quality gradually weakens; (2) The space for increasing the sinter alkalinity is limited, and the price of quicklime is relatively high. Increasing the proportion of quicklime increases the cost and reduces the economy; (3) When the amount of quicklime increases, if the enterprise's own output cannot meet the production demand, the quicklime is purchased from outside, which easily leads to the fluctuation of sinter quality and the deterioration of index due to the fluctuation of quicklime quality.

[0017] The present application is used to solve the technical problems of strengthening sintering granulation and balling, improving the permeability of the material layer, and improving the sinter quality.

[0018] A method for adding bentonite to improve the sinter quality, comprising the following steps: (1) Bentonite selection: imported bentonite and domestic bentonite both have the effect of strengthening granulation and balling; (2) Sintering mixed raw material batching calculation: according to the required technical quality indexes of sinter, the addition proportions of iron-containing raw materials, flux, sintering return fines, flux and solid fuel are calculated, the iron-containing raw materials (hematite, limonite, magnetite, etc.) are 65-80%, the sintering return fines are 5-25%, the bentonite is 0-0.5%, the flux is 6-12% (of which, the quicklime is 3-6%), and the solid fuel (coal, powdered coke, etc.) is dynamically added at a unit consumption of 40-70 kg / ton of sinter. The sum of the mass percentages of each component is 100%. The produced finished sinter has a basicity of 1.75-2.2 and a magnesium oxide content of 1.2-2.0%.

[0019] (3) After the raw materials are mixed and granulated and balling in the first mixing and second mixing processes according to the calculated proportions, the materials are distributed and sintered on the sintering machine. During the sintering process, the material layer thickness is appropriately adjusted according to the real-time induced draft negative pressure monitoring. Example 1

[0020] The calculation process of the sintering cup experiment without adding bentonite is as follows: the ore powder is mixed according to different proportions to obtain ore powder mixture component 1, the sinter basicity target is set to 1.8, the magnesium oxide content is 1.5%, the corresponding proportions of flux components such as quicklime and limestone are calculated according to the experiment, and the sinter component 1 is obtained, in which the quicklime proportion is 4%. In Example 1, the ore powder and flux are fully mixed and formed, small particles adhere to the periphery of large particles, and the effect of quicklime granulation and balling is mainly achieved. The morphology of the material after the ore powder and flux are fully mixed in Example 1 is shown in Figure 1 , and the data comparison table is shown in Table 1.

[0021] Table 1 Data comparison table of Example 1 . Example 2

[0022] The calculation process of the sintering cup experiment with the addition of 0.2% bentonite is as follows: the iron-containing raw material proportion is adjusted according to the batching calculation of the sinter component target in Example 1 to obtain ore powder mixture component 2, the sinter basicity target is 1.8, the magnesium oxide content is 1.5%, and the corresponding proportions of flux components such as quicklime and limestone are calculated according to the experiment. The sinter component 2 is calculated, the ore powder mixture, flux and 0.2% bentonite are fully mixed, and the morphology of the material is shown in Figure 2 . The morphology is approximately uniform small balls, and the particle size is uniform. Compared with the morphology after mixing in Example 1, the bentonite further strengthens the effect of granulation and balling on the basis of quicklime, which can effectively improve the air permeability of the material during the sintering process. The data comparison table is shown in Table 2.

[0023] Table 2 Example 2 Data Control Table .

[0024] The above merely illustrates the technical solutions of the present application, and simple modifications or equivalent replacements of the technical solutions of the present application made by those skilled in the art do not deviate from the essence and scope of the technical solutions of the present application.

Claims

1. A method of improving sinter quality by addition of bentonite, characterised by: The method comprises the following steps: Step 1) according to the target composition of sinter, the ratio of iron-containing raw materials used for sintering, lime-based flux, solid fuel and bentonite is calculated, and 0-0.5% of bentonite by weight is added; Step 2) the iron-containing raw materials, flux, solid fuel and bentonite mixed in step 1) are cut out from the batching bin and sent to the mixing area for mixing, then water is added and mixed uniformly, and the mixed material is bonded into particles; Step 3) the particles bonded in step 2) are sent to the sintering trolley for distribution to the sintering machine, and air is drawn for sintering.

2. The method of improving sinter quality by adding bentonite according to claim 1, characterized in that: The main component of the bentonite is montmorillonite and a mixture containing montmorillonite, and the silicon content of the comprehensive component is 40%-75%, and the aluminum content is 10%-25%.

3. The method of adding bentonite to improve sinter quality as claimed in claim 1 wherein: In step 2), the bentonite is cut out by a screw feeder or a disc feeder at a small flow rate, and is sent to the mixing area to be mixed uniformly with other sintering raw materials.

4. The method of adding bentonite to improve sinter quality as claimed in claim 1 wherein: In step 2), the mixing area comprises a mixing process and a secondary mixing process.

5. The method of improving sinter quality by adding bentonite as claimed in claim 1 wherein: In step 2), the average particle size of the mixed material bonded into particles is greater than 2.5 mm.

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