A method for predicting the particle size distribution of a sinter mix

Abstract

The present application belongs to the technical field of steel metallurgy, and particularly relates to a prediction method of sintering mixture particle size composition. The present application is based on the theory that the core particles of sintering mixture are mainly natural iron ore and the particle quantity is stable. The direct mathematical relationship between the particle distribution of original iron ore and the particle size distribution of sintering mixture is established by constructing the distribution model of natural iron ore as the core particle and the prediction method of the final sintering mixture particle size composition is established. The method directly crosses the most influencing factors and the most difficult to quantify process such as the water granulation process, thereby directly crossing the most difficult to quantify process such as the mixing and granulation process, solving the most key problem of the prediction mixture particle size distribution accuracy, fundamentally solving the key problem of the mixture particle size composition prediction, and being simple, efficient and easy to apply in the production site.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of iron ore sintering, in particular to a method for predicting the particle size composition of sintering mixture. BACKGROUND

[0002] The preparation of finished sintered ore from sintering raw material iron ore needs to go through the steps of uniform mixing, mixing granulation, high-temperature sintering, cooling and granulation, etc., so the sintering ore blending must meet the comprehensive evaluation requirements of raw material composition, particle size composition, metallurgical properties, economic indicators, etc.

[0003] In China, there are many types of iron ore powder used in sintering production, with varying performance, quality and poor stability. In order to meet the needs of production for iron ore raw materials, steel enterprises must use a variety of ores with different performance and quality, which puts forward higher requirements for sintering optimized ore blending. High-quality ore blending structure can effectively improve the quality of sintered ore, and thus improve the ironmaking indicators of blast furnace, so the optimization of ore blending has an important influence on the stability, efficiency and economy of sintering and ironmaking processes. The granulation process of raw materials such as iron ore, flux, fuel and miscellaneous materials plays a role in connecting the upstream and downstream in the whole sintering process, and the particle size composition of the sintering mixture after granulation determines the permeability of the whole sintering process, which plays a crucial role in the quality and yield of sintered ore.

[0004] However, due to the numerous factors affecting the sintering mixing granulation process and the difficulty in quantification, it is impossible to accurately monitor the online mixture particle size under the existing technical conditions. Although many studies have been conducted in this regard at home and abroad, mainly involving raw material properties, mixing time, optimization of cylinder granulation parameters, water quantity and method, etc., different models for predicting the final particle size have been developed, but most of the research results are still far from field application; and the original intention of almost all models is to change the granulation process to adapt to the characteristics of raw fuel, rather than to change the characteristics of raw fuel to adapt to the granulation process, which undoubtedly greatly increases the difficulty and cost of perfecting the process.

[0005] In summary, in the production of iron ore sintering, it is necessary to establish a simple, efficient and easy-to-use sintering mixture model for the production site to accurately predict the particle size distribution of the mixture of different material piles. SUMMARY

[0006] In order to overcome the shortcomings of the prior art, the present application provides a method for predicting the particle size composition of sintering mixture, which solves the problems of accuracy and timeliness of predicting the particle size distribution of the mixture, makes it possible to predict the particle size distribution of the mixture under different ore blending schemes, and thus improves the yield and quality of sintered ore.

[0007] In order to achieve the above-mentioned purpose, the present application adopts the following technical scheme:

[0008] The application relates to a method for predicting the particle size composition of a sintering mixture, which comprises the following steps:

[0009] Step 1) screening the natural iron ores in the sintering ore matching scheme according to the particle size grades of L>8mm, 5mm<=L<=8mm, 3mm<=L<5mm, 1mm<=L<3mm and L<1mm, wherein L is the particle size of the natural iron ore, mm, and the total distribution of each particle grade of different kinds of natural iron ores is obtained from the following formula:

[0010] the total sum of the particle size of L>8mm

[0011] the total sum of the particle size of 5mm<=L<=8mm

[0012] the total sum of the particle size of 3mm<=L<5mm

[0013] the total sum of the particle size of 1mm<=L<3mm

[0014] the total sum of the particle size of L<1mm

[0015] In the formula, T i is the matching proportion of the i kinds of natural ores, %;

[0016] Ai is the proportion of the particle size of L>8mm in the particle size composition of the i kinds of natural iron ores, %;

[0017] Bi is the proportion of the particle size of 5mm<=L<=8mm in the particle size composition of the i kinds of natural iron ores, %;

[0018] Ci is the proportion of the particle size of 3mm<=L<5mm in the particle size composition of the i kinds of natural iron ores, %;

[0019] Di is the proportion of the particle size of 1mm<=L<3mm in the particle size composition of the i kinds of natural iron ores, %;

[0020] Ei is the proportion of the particle size of L<1mm in the particle size composition of the i kinds of natural iron ores, %.

[0021] Step 2) pre-particle sizing according to the sintering ore matching scheme before production, and screening the sintering mixture after particle sizing according to the particle size grades of L 制粒后的烧结混合料 >8mm, 5mm<=L 制粒后的烧结混合料 <=8mm, 3mm<=L 制粒后的烧结混合料 <5mm, 1mm<=L 制粒后的烧结混合料 <3mm and L 制粒后的烧结混合料 <1mm, wherein L 制粒后的烧结混合料Particle size of sintering mixture after granulation, mm.

[0022] The sintering mixtures of the above-mentioned particle size levels of >8 mm, 5-8 mm, 3-5 mm and 1-3 mm are respectively screened and measured by water screening and / or microscopy to obtain sintering mixtures with natural iron ore particles of different particle levels as core particles, and the percentage contents of the sintering mixtures are respectively K1, K2, K3 and K4.

[0023] Step 3) L 烧 Particle size of sintering mixture, mm, and the particle size composition of the sintering mixture is as follows:

[0024] L 烧 Percentage content of particle size level of >8 mm = L >8 / K1,

[0025] 5 mm≤L 烧 Percentage content of particle size level of ≤8 mm = L 5-8 / K2,

[0026] 3 mm≤L 烧 Percentage content of particle size level of <5 mm = L 3-5 / K3,

[0027] 1 mm≤L 烧 Percentage content of particle size level of <3 mm = L 1-3 / K4,

[0028] L 烧 Percentage content of particle size level of <1 mm = N×M-R / S;

[0029] In the formula, N is the ratio of the actual solid fuel content in the particle size level of <1 mm to the total solid fuel content in the whole mixture to the percentage content of fuel in the particle size level of <1 mm;

[0030] R is the addition ratio of natural iron ore powder in the sintering ore matching scheme, %;

[0031] S is the addition ratio of concentrate in the sintering ore matching scheme, %;

[0032] M is the addition ratio of total fuel in the sintering ore matching scheme, %, and M is the dry amount.

[0033] The fuel is one or more of coke powder, coal powder and biomass fuel.

[0034] As a further improvement of the technical scheme of the present application, the mixture is cooled in liquid nitrogen for more than 3 minutes during the screening in step 1).

[0035] As a further improvement of the technical scheme of the present application, the value of N in step 3) is 2.6-4.5.

[0036] As a further improvement of the technical scheme of the present application, when the concentrate ratio in step 3) is 0, L 烧 <1mm particle size level percentage content = N x M-10%.

[0037] Compared with the prior art, the present application has the following beneficial effects:

[0038] 1. In the sintering granulation process mainly using fine ore, the formed pellets have high particle strength and are not easy to be damaged, and multiple particles will not continuously aggregate and grow, and most of them have reached the final particle diameter within about 2-3 minutes, and the number of formed particles is also relatively stable.

[0039] The present application is based on the theory that the core particles of the sintering mixture are mainly natural iron ore, and the particle number is stable, and by constructing a distribution model of the natural iron ore as the core particle, a direct mathematical relationship between the particle distribution of the original iron ore and the particle size distribution of the sintering mixture is established, and a prediction method for the particle size composition of the final sintering mixture is established.

[0040] The method directly crosses the water granulation process which has the most influencing factors and the most difficult process to be quantified, thereby directly crossing the mixing and granulation process which is most difficult to be quantified, solving the most critical problem of predicting the particle size distribution of the mixture, and fundamentally solving the key problem of predicting the particle size composition of the mixture, and being simple, efficient and easy to be applied in production site.

[0041] 2. In the present application, the mixture is cooled in liquid nitrogen for more than 3 minutes during screening. By cooling the mixture in liquid nitrogen, the moisture in the mixture can be quickly locked, reducing the adhesion between the mixture and the screening device, and the screening is more accurate and efficient.

[0042] 3. In the present application, the value of N is set to 2.6-4.5, K1 is 70%-80%, K2 is 65%-75%, K3 is 55%-65%, and K4 is 60%-75%. Using the principle of mixture core particle balling, the prediction accuracy of the particle size distribution of the mixture can be quickly and accurately improved, and it is easy to operate in production site.

[0043] 4. In the present application, when the concentrate ratio is 0, L 烧 <1mm particle size level percentage content = N x M-10. The prediction accuracy can be improved. DETAILED DESCRIPTION

[0044] The present application discloses a method for predicting the particle size composition of sintering mixture. Those skilled in the art can improve the process parameters according to the content herein. It is particularly pointed out that all similar substitutions and changes are obvious to those skilled in the art, and they are considered to be included in the present application. The method and application of the present application have been described by the preferred embodiments, and the relevant personnel can obviously make changes or appropriate changes and combinations to the method and application described herein without departing from the content, spirit and scope of the present application, to realize and apply the present application technology.

[0045] A method for predicting the particle size composition of sintering mixture, in the iron ore sintering production process, the particle size composition of each sintering mixture after granulation is predicted by the original particle size distribution of natural iron ore, which specifically includes the following steps:

[0046] Step one, according to the sintering ore matching scheme of each sintering mixture, the total matching ratio of natural iron ore is R, the matching ratio of concentrate is S, and the total fuel ratio is M (dry weight). The natural iron ore in the ore matching scheme is sieved according to the particle size level of >8mm, 5-8mm, 3-5mm, 1-3mm and <1mm, and the total distribution of each particle size of different natural iron ore is obtained by the following formula:

[0047] The sum of particle size greater than 8mm:

[0048] The sum of particle size of 5-8mm:

[0049] The sum of particle size of 3-5mm:

[0050] The sum of particle size of 1-3mm:

[0051] The sum of particle size of <1mm:

[0052] The fuel is a mixture of one or more of coke powder, coal powder and biomass fuel.

[0053] In the formula, Ti is the matching ratio of i kinds of natural ore, %; Ai is the proportion of >8mm in the particle size composition of i kinds of natural iron ore, %; Bi is the proportion of 5-8mm in the particle size composition of i kinds of natural iron ore; Ci is the proportion of 3-5mm in the particle size composition of i kinds of natural iron ore, %; Di is the proportion of 1-3mm in the particle size composition of i kinds of natural iron ore; Ei is the proportion of <1mm in the particle size composition of i kinds of natural iron ore.

[0054] Step two, according to the ore proportioning scheme, pre-pelletizing before production, and screening the sintered mixture after pelletizing according to the particle size levels of >8mm, 5-8mm, 3-5mm, 1-3mm, and <1mm, and using water screen and microscope to screen and measure the core particles of the mixture with particle sizes of >8mm, 5-8mm, 3-5mm, and 1-3mm, respectively, to obtain the percentage content of natural iron ore as core particles in different particle levels, which are K1, K2, K3, and K4, respectively. When screening the particle size of the mixture, the mixture needs to be cooled in liquid nitrogen for more than 3 minutes.

[0055] Step three, in the particle size composition of the sintered mixture:

[0056] The percentage content of particle size level of >8mm = L >8 / K1,

[0057] The percentage content of particle size level of 5-8mm = L 5-8 / K2,

[0058] The percentage content of particle size level of 3-5mm = L 3-5 / K3,

[0059] The percentage content of particle size level of 1-3mm = L 1-3 / K4,

[0060] The percentage content of particle size level of <1mm = N x M - R / S.

[0061] N is the ratio of the actual solid fuel content in the particle size level of <1mm to the total solid fuel content in the entire mixture to the percentage content of fuel in the particle size level of <1mm, and its value range is 2.6-4.5.

[0062] When the concentrate ratio is 0, the percentage content of particle size level of <1mm = N x M - 10%.

[0063] According to the particle size variation of the iron ore powder, the range of K1 is 70%-80%, the range of K2 is 65%-75%, the range of K3 is 55%-65%, and the range of K4 is 60%-75%.

[0064]

EXAMPLE

[0065] The natural iron ore for sintering production is screened, and the original particle size composition of the natural iron ore is shown in Table 1.

[0066] Table 1 Original particle size distribution of natural iron ore

[0067] High Brazil powder Yangdi powder Newman powder Ha powder Roy Hill Concentrate > 8 mm 12.70 26.90 11.70 11.71 23.63 5-8 mm 17.90 22.80 18.10 16.02 27.85 3-5 mm 17.50 21.20 17.10 18.21 15.15 1-3 mm 24.40 18.70 26.50 24.79 17.62 < 1 mm 27.50 10.40 26.70 29.28 15.75 100

[0068] Example 1:

[0069] According to the resource and ore blending requirements, the ore blending scheme of natural iron ore is as shown in Table 2.

[0070] Table 2 Ore blending scheme %

[0071] High Brazil powder Yangdi Newman powder Ha powder Roy Hill Concentrate Proportion 20.08 16.96 0 32.5 6.7 9.91

[0072] The scheme uses coke powder as fuel, and the addition amount is 4.1% (dry weight), and the comprehensive distribution of different particle sizes of natural iron ore is obtained as shown in Table 3.

[0073] Table 3 Comprehensive distribution of particle size of different natural ores %

[0074] > 8 mm 5-8 mm 3-5 mm 1-3 mm < 1 mm Natural ore 12.50 14.53 14.04 17.31 27.77

[0075] According to the ore blending scheme, pre-granulation is carried out before production, and after the granulated sintering mixture is frozen in liquid nitrogen for 4 minutes, it is sieved according to the particle size levels of >8mm, 5-8mm, 3-5mm, 1-3mm and <1mm, and the mixture of >8mm, 5-8mm, 3-5mm and 1-3mm particle size is sieved and measured by water sieve and microscope respectively to obtain the percentage content of natural iron ore as core particle in different particle sizes, which is shown in Table 4.

[0076] Table 4 Core particle content of iron ore %

[0077] Mass content of iron ore core particles, % [K1] 75 [K2] 74 [K3] 62 [K4] 64

[0078] The ratio of the actual fuel content in the <1mm particle size level to the total fuel content is 3.6, and the comparison between the predicted results and the actual results of the mixture particle size is shown in Table 5 according to the calculation formula.

[0079] Table 5 Comparison between actual detection results and predicted results

[0080] ％ > 8 mm 5-8 mm 3-5 mm 1-3 mm < 1 mm Average particle size Predicted particle size 18.206 21.452 24.739 29.539 6.065 4.73 mm Measured particle size 18.1 21.5 25.2 29.8 6.1 4.75 mm

[0081] From the comparison between the predicted results and the actual results, the difference between the average particle sizes is only 0.02mm, and the difference in particle size composition is within the error range, which shows that the prediction method is very targeted and the results are very accurate.

[0082] Example 2:

[0083] According to the resource and ore blending requirements, the ore blending scheme of natural iron ore is as shown in Table 6.

[0084] Table 6 Ore blending scheme %

[0085] High Brazil powder Yangdi Newman powder Ha powder Roy Hill Concentrate Proportion 19.46 17.33 9.97 23.91 6.99 9.92

[0086] The scheme produces fuel as coke powder, and the addition amount is 4.2% (dry weight), and the comprehensive distribution of different natural iron ore particle sizes is obtained, as shown in Table 7.

[0087] Table 7 Particle size comprehensive distribution of different natural ores

[0088] > 8 mm 5-8 mm 3-5 mm 1-3 mm < 1 mm Natural ore 12.75 15.02 14.19 17.79 27.84

[0089] According to the ore matching scheme, pre-granulation is carried out before production, and after the granulated sintering mixture is frozen in liquid nitrogen for 5 minutes, it is sieved according to the particle size levels of >8mm, 5-8mm, 3-5mm, 1-3mm and <1mm, and the >8mm, 5-8mm, 3-5mm and 1-3mm particle size mixtures are respectively screened and measured for core particles using water screen and microscope, and the percentage of natural iron ore as core particles in different particle sizes is shown in Table 8.

[0090] Table 8 Core particle content of iron ore

[0091] Mass content of iron ore core particles, % [K1] 74 [K2] 70 [K3] 60 [K4] 67

[0092] The ratio of the actual fuel content in the <1mm particle size level to the total fuel content is 3.55, and the predicted results of the mixture particle size are compared with the actual results according to the calculation formula, as shown in Table 9.

[0093] Table 9 Comparison of actual detection results and predicted results

[0094] ％ > 8 mm 5-8 mm 3-5 mm 1-3 mm < 1 mm Average particle size Predicted particle size 18.244 22.712 25.035 28.112 5.897 4.80 mm Measured particle size 17.9 23.1 25.0 28.0 6.2 4.79 mm

[0095] From the comparison of the predicted results and the actual results, the difference between the average particle sizes is only 0.01mm, and the difference in particle size composition is within the error range, so the prediction method is very targeted and the results are very accurate.

[0096] Example 3:

[0097] According to the resource and ore matching requirements, the ore matching scheme of natural iron ore is as follows in Table 10.

[0098] Table 10 Ore matching scheme

[0099] High Brazil powder Yangdi Newman powder Ha powder Roy Hill Concentrate Proportion 25.97 11.86 16.81 25.77 4.75 0

[0100] The scheme produces fuel as coke powder, and the addition amount is 4.3% (dry weight), and the comprehensive distribution of different natural iron ore particle sizes is obtained, as shown in Table 11.

[0101] Table 11 Particle size comprehensive distribution of different natural ores

[0102] > 8 mm 5-8 mm 3-5 mm 1-3 mm < 1 mm Natural ore 12.60 15.85 15.33 20.23 21.16

[0103] According to the ore blending scheme, the sintered mixture after pre-granulation is screened in liquid nitrogen for 5 minutes according to the particle size levels of >8mm, 5-8mm, 3-5mm, 1-3mm and <1mm, and the core particles of the mixtures with particle sizes of >8mm, 5-8mm, 3-5mm and 1-3mm are screened and measured by water screening and microscopy, respectively, to obtain the percentage of natural iron ore as core particles in different particle levels, which is shown in Table 12.

[0104] Table 12 Percentage of core particles of iron ore

[0105] Mass content of iron ore core particles, % K1 78 K2 72 K3 65 K4 70

[0106] The ratio of the actual fuel content in the <1mm particle size level to the total fuel content is 3.6, and the concentrate ratio is 0, so the comparison between the predicted results and the actual results of the mixture particle size is shown in Table 13 according to the calculation formula.

[0107] Table 13 Comparison between actual detection results and predicted results

[0108] ％ > 8 mm 5-8 mm 3-5 mm 1-3 mm < 1 mm Average particle size Predicted particle size 16.799 22.896 24.534 30.071 5.701 4.70 mm Measured particle size 17.4 23.2 24.6 30.2 5.5 4.78 mm

[0109] From the comparison between the predicted results and the actual results, the difference between the average particle sizes is only 0.08mm, which shows that the prediction method is very targeted and the results are very accurate.

[0110] The present application directly establishes the mathematical relationship between the particle distribution of the original iron ore and the particle size distribution of the sintered mixture by constructing the distribution model of the natural iron ore as the core particle, thereby directly crossing the most difficult to quantify mixing and granulation process, solving the most key problem that has been plagued by the prediction of the sintered mixture particle size distribution accuracy, making it possible to predict the sintered mixture particle size distribution under different ore blending schemes, providing technical guidance for optimizing ore blending and reasonably purchasing ore, and thereby improving the yield and quality of the sintered ore.

[0111] The present application can be matched with various iron ores with different particle size distributions to reasonably utilize various iron ore resources to improve the sintered ore quality, reduce energy consumption, reduce production cost and improve the market competitiveness of enterprises by model prediction under the premise of meeting the sintered raw material ratio calculation.

[0112] The above is only the preferred specific implementation of the present application, but the protection scope of the present application is not limited thereto, any skilled person in the art can make equivalent replacement or change according to the technical solution and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A method of predicting the particle size distribution of a sinter mix, characterised in that, The method comprises the following steps of: Step 1) screen the natural iron ore in the sintering ore matching scheme according to the particle size grades of L>8mm, 5mm≤L≤8mm, 3mm≤L<5mm, 1mm≤L<3mm and L<1mm, L is the particle size of the natural iron ore, mm, and the total distribution of each particle grade of different kinds of natural iron ores is obtained from the following formula: L > 8 mm size sum 5 mm < L < 8 mm sum of the particle sizes 3 mm < L < 5 mm sum of the particle sizes 1 mm < L < 3 mm sum of the particle sizes L < 1 mm size fraction wherein: T i is the proportion of i natural minerals, %; Ai is the proportion of L>8mm in the particle size composition of the i-th natural iron ore, %; Bi is the proportion of 5mm≤L≤8mm in the particle size composition of the i-th natural iron ore, %; Ci is the proportion of 3mm≤L<5mm in the particle size composition of the i-th natural iron ore, %; Di is the proportion of 1mm≤L<3mm in the particle size composition of the i-th natural iron ore, %; Ei is the proportion of L<1mm in the particle size composition of the i-th natural iron ore, %; Step 2) Pre-pelletizing is carried out before production according to the sintering proportioning scheme, and the pelletized sintering mixture is screened according to L 制粒后的烧结混合料 >8mm, 5mm≤L 制粒后的烧结混合料 ≤8mm, 3mm≤L 制粒后的烧结混合料 <5mm, 1mm≤L 制粒后的烧结混合料 <3mm, L 制粒后的烧结混合料 <1mm size grade, L 制粒后的烧结混合料 is the particle size of the pelletized sintering mixture, mm; Screen and measure the sintering mixture of different particle grades with the natural iron ore as the core particle, and the percentage contents of the sintering mixture are K1, K2, K3 and K4 respectively; Step 3) L 烧 For sintered mixture particle size, mm, the sintered mixture particle size composition is as follows: L 烧 >8 mm particle size fraction = L >8 / K1, 5 mm < L 烧 Percentage content of the size fraction of ≤ 8 mm = L 5-8 / K2, 3 mm < L 烧 Percentage content of the size fraction < 5 mm = L 3-5 / K3, 1 mm < L 烧 Percentage content of the size fraction < 3 mm = L 1-3 / K4, L 烧 <1 mm size fraction percentage content = N x M - R / S; In the formula, N is the ratio of the actual solid fuel content in the particle size grade of <1mm to the total solid fuel content in the whole mixture to the percentage content of fuel in the particle size grade of <1mm; R is the addition ratio of the natural iron ore powder in the sintering ore matching scheme, %; S is the addition ratio of the concentrate in the sintering ore matching scheme, %; M is the addition ratio of the total fuel in the sintering ore matching scheme, %, M is the dry content.

2. A method of predicting the particle size distribution of a sinter mix according to claim 1 characterised in that, In the step 2), when the particle size of the sintering mixture after granulation is screened, the mixture is cooled in liquid nitrogen for more than 3 minutes.

3. The method for predicting the particle size distribution of sintered mixtures according to claim 1, characterized in that, In the step 2), the sintering mixture of different particle grades is screened and measured by using the water screen and / or microscope to obtain the sintering mixture with the natural iron ore as the core particle.

4. The method for predicting the particle size distribution of a sintering mixture according to claim 1, characterized in that, In the step 3), the fuel is one or more of coke powder, coal powder and biomass fuel.

5. The method of claim 1, wherein the sintering mixture particle size distribution is predicted by the equation: ###0001### where: P is the predicted sintering mixture particle size distribution; and D is the desired sintering mixture particle size distribution. In the step 3), the value of N is 2.6-4.

5.

6. The method of claim 1, wherein the sintering mixture particle size distribution is predicted by the equation: ###0001### where: P is the predicted sintering mixture particle size distribution; and D is the desired sintering mixture particle size distribution. The step 3) concentrate ratio is 0, L 烧 <1 mm particle size level percentage content = N x M - 10%.

7. The method for predicting the particle size distribution of a sintering mixture according to claim 1, characterized in that, In the step 3), according to the particle size of the iron ore powder, K1 is 70%-80%, K2 is 65%-75%, K3 is 55%-65% and K4 is 60%-75%.

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