A method for determining the moisture content of sintering material suitable for granulation

Abstract

A method for determining the moisture content of sintering materials suitable for granulation, comprising the following steps: preparing samples; determining the saturated moisture content of two particle size samples; and calculating the measured value of moisture suitable for granulation of the detection object. The present invention does not require a large number of tests and linear regression model derivation, but can obtain the moisture content suitable for sintering granulation through simple sample processing measurement and formula addition calculation, thereby providing more accurate guidance and services for on-site production.

Description

Technical Field

[0001] The invention relates to the field of metallurgical sintering pellets, and in particular to a method for determining the moisture content of a sintering material suitable for pelletizing. Background Art

[0002] Sintering granulation is an important part of the sintering process, and moisture plays a vital role in the granulation process. A search found that the article "PSO-BP Control Algorithm for Granulation Process Based on Particle Size Distribution Evaluation and Optimization" published in "Acta Automatica Sinica" in 2012 pointed out that the moisture in the granulation process includes molecular adsorbed water, capillary water and gravity water. The bonding between ore particles requires the capillary liquid bridge force formed by the water on the surface of the particles, and the amount of adsorbed water on the surface of the ore particles is affected by the water absorption capacity of the ore. When the amount of water added is small, most of the water enters the pores inside the ore particles, while the moisture on the surface of the particles is insufficient, so the granulation performance is not good. On the contrary, when the amount of water added exceeds the range of the capillary liquid bridge force suction, gravity water is formed, which has a negative impact on the granulation process. This paper qualitatively describes the impact of moisture in the granulation process, and uses the self-learning artificial intelligence method to establish a relationship model between moisture and particle size distribution. The fitting accuracy is only 94%, which cannot be used for the evaluation of moisture suitability. In order to improve the granulation performance, the amount of added water must be adjusted within a suitable range according to the water absorption capacity of each ore so that a capillary liquid bridge is formed on the particle surface and the capillary liquid bridge force reaches the maximum, which is the saturated capillary water of the mineral powder. For the measurement of mineral powder capillary water, the most widely used are the maximum capillary water of iron ore powder and the wet capacity proposed in recent years, such as the literature "An instrument for measuring the ball-forming index of iron ore concentrate" (Chinese patent, 2012) and (published in the Journal of Chongqing University, 2011) "The concept of wet capacity of iron ore powder and its application in the granulation process" proposed the concept of wet capacity and published the test method of wet capacity, indicating that the measurement of the maximum capillary water and wet capacity of iron ore powder are both carried out under the natural stacking state of iron ore powder, which is inconsistent with the particle size field distribution state after granulation.

[0003] If the suitable moisture content is predicted based on this measured value, deviations will also occur, as described in the following three documents: "Effects of binders on balling behaviors of iron ore concentrates" published in Scandinavian Journal of Metallurgy, 2004, "Prediction of Suitable Moisture Content of Sintered Mixtures for Granulation" published in Journal of University of Science and Technology Beijing in 2012, which tested capillary water and proposed a formula for calculating suitable moisture content for granulation using capillary water, and the document "A Method for Granulating Iron Ore Powder" (Chinese Patent, 2012) announced a method for predicting suitable moisture content for granulation by wet volume, the steps of which are analyzing and testing the wet volume of the material - predicting the suitable amount of water to be added - preparing the modifying liquid - adding the modifying liquid - mixing and granulating - exhaust sintering. These three documents use linear regression to establish the relationship between the maximum capillary water and wet volume of the iron ore powder and the measured values ​​thereof, that is, to calculate the regression formula from the detected data, and find a formula that minimizes the deviation between the calculated result and the existing data, so as to predict the suitable moisture content of the mixture for granulation by this formula. After the iron ore powder is granulated by the cylinder, the particle size field between the particles is the particle size field distribution state after extrusion. Due to the different properties of different iron ore powders, the degree of extrusion will be different under the same conditions. Therefore, the capillary water volume and wet capacity measured under the natural stacking state are used to predict the suitable granulation moisture. There will be different degrees of deviation, and the measured moisture is less consistent with the sintering material granulation moisture. Therefore, the result predicted by the formula in the literature is: when the absolute error of the suitable granulation moisture is ±0.3%, the prediction accuracy can reach 93.3%, and the precision is relatively low. The document "The influence of water absorption behavior of raw materials on the optimal amount of water added during sintering and granulation" (published in the 2010 China-Japan bilateral technical exchange and investigation collection, 2011) also proposed that saturated water content characterizes the water absorption capacity of ore, and uses saturated water absorption to predict the appropriate granulation moisture. The detection method of saturated water absorption is: take a sample of a specified particle size and dry it at 105℃±5℃ for 12 hours, then put the sample of known mass into a cloth bag and soak it in water for 24 hours; after soaking, dehydrate the sample for 10 minutes to remove the surface adsorbed water ; Then put the dehydrated sample into a dryer (105℃±5℃) and dry it for minutes to evaporate the surface water, weigh it, and record it as wet weight (Sw); then dry the sample at 105℃±5℃ for 12 hours and weigh it, record it as dry weight (Sd), and use the equation (Sw-Sd) / Sw to calculate the saturated water content. This method cannot detect the saturated water content of mineral powder in a stacked state, and the parameters used in this method to remove surface water and dry surface water make it impossible to judge the degree of surface water removal. Therefore, this method cannot guarantee that the measured moisture is saturated water. Summary of the invention

[0004] The present invention aims to overcome the problem that the prior art cannot directly measure and calculate the moisture content suitable for granulation, and provides a method for measuring the saturated capillary water content of particles according to the particle size field distribution state of the particles during granulation, and calculating the moisture content of the sintering material suitable for granulation on site.

[0005] Measures to achieve the above objectives:

[0006] A method for determining the moisture content of sintering material suitable for granulation, wherein the determination steps are as follows:

[0007] 1) Prepare the sample

[0008] A. Obtaining samples: Use a uniform multi-point sampling method to obtain sample materials, and control the total amount of sample materials obtained to be no less than 3000g;

[0009] B. Place the sample in an oven for drying, control the drying temperature to be no less than 100°C, and the drying time to be no less than 2 hours, until the moisture content is ≤ 0.05wt%; then weigh the weight and mark it as M. 总重 ;

[0010] C. Screening: Take out the dried sample and screen it with a 0.5mm sieve to screen out two kinds of particle size samples: one with a particle size greater than 0.5mm and one with a particle size ≤0.5mm; and mark them as M respectively. +0.5总重 and M -0.5总重 ;

[0011] D. Calculate the weight percentage of the samples with particle size greater than 0.5 mm and particle size ≤ 0.5 mm, respectively, and record them as M +0.5mm wt% and M -0.5mm wt%;M +0.5mm wt%=M +0.5总重 ÷M 总重 *100wt%,M -0.5mm wt%=M -0.5总重 ÷M 总重 *100wt%;

[0012] E. Soak the samples with particle size greater than 0.5mm and ≤0.5mm separately: take a weight of not less than 50g for the sample with particle size greater than 0.5mm and take a weight of not less than 400g for the sample with particle size ≤0.5mm, put them into containers respectively, add water until they are submerged, and soak for not less than 48 hours;

[0013] F. After taking out the samples, wipe off the moisture on the surface of the samples, and then use absorbent paper to test. Stop wiping when there is no trace of water absorption on the absorbent paper;

[0014] 2) Determine the saturated water content of the two particle size samples

[0015] A. The saturated water content of samples with a particle size greater than 0.5 mm is determined by the flat spreading method, that is, the sample is spread flat on the container and allowed to enter the subsequent water absorption state within 5 minutes after it is completely spread out without accumulation;

[0016] B. For samples with a particle size of ≤0.5mm, place two samples in the following manner: one of them is placed in a columnar container with a height scale by natural drop. When the sample is placed to a height of H1, the weight of the sample is recorded. H1 is controlled between 50 and 100mm.

[0017] The other is to load the sample by extrusion and stacking in layers. The sample with the same weight as the natural falling loading method is loaded in the following way. When the material layer is any fixed value of 4-5mm thickness, a fixed external force and the same number of extrusions are used to extrude the material layer. After the sample is loaded, the height H2 of the loaded sample is recorded; when the ratio of H2 / H1 reaches 70-80% after extrusion, the subsequent water absorption state is entered within 5 minutes after stopping extrusion;

[0018] C. The sample absorbs water until it is saturated: Place the sample with a particle size greater than 0.5 mm after being flattened by the flattening method together with the vessel, and the sample with a particle size ≤ 0.5 mm after being squeezed and stacked together with the sample bottle into a closed container; allow the sample to fully absorb the water in the space in the closed container until it reaches a saturated state;

[0019] Weighing of the sample when it reaches saturated water content: Take out the sample bottles containing the sample from the sealed container and weigh the wet weight of the sample at this time. Samples with a particle size greater than 0.5 mm are marked as m 湿+0.5mm After extrusion and stacking, the sample with a particle size of ≤0.5mm is marked as m 湿-0.5mm ;

[0020] D. Put the weighed wet sample into an oven for drying at a temperature not lower than 100°C for at least 2 hours until the moisture content does not exceed 0.05wt%. Take out the dried sample and weigh it respectively. Samples with a particle size greater than 0.5mm are marked as m. 干+0.5mm , the sample with particle size ≤ 0.5 mm is marked as m 干-0.5mm ;

[0021] E. Use the following formula to calculate the saturated capillary water content Q of the two samples with a particle size greater than 0.5 mm and a particle size ≤ 0.5 mm: The saturated capillary water content of the sample with a particle size greater than 0.5 mm is recorded as Q +0.5mm wt%, the saturated capillary water content of the sample with a particle size of ≤0.5 mm is recorded as Q- 0.5mm wt%;

[0022] Q=(m 湿 –m干 ) / m 湿

[0023] Where: m 湿 —It indicates the weight of the sample with a particle size greater than 0.5 mm or a particle size ≤ 0.5 mm after absorbing the water in the space of the closed container until it reaches a saturated state and no longer changes, in g;

[0024] m 干 —Indicates the weight of the sample after drying for a particle size greater than 0.5 mm or a particle size ≤ 0.5 mm, in g;

[0025] 3) Calculation of the moisture content of the granulated object to be tested, the calculation formula is:

[0026] (M +0.5mm *Q +0.5mm +M -0.5mm *Q -0.5mm ) / 100

[0027] Where: M +0.5mm —Indicates the weight percentage of the sample with a particle size greater than 0.5 mm after screening, in wt%;

[0028] M -0.5mm —Indicates the weight percentage of the sample with a particle size of ≤0.5mm after screening, in wt%;

[0029] Q +0.5mm —Indicates the saturated capillary water content of samples with a particle size greater than 0.5 mm, in wt%;

[0030] Q -0.5mm —Indicates the saturated capillary water content of the sample with a particle size of ≤0.5 mm, in wt%.

[0031] The invention is characterized in that: the detected sintering material is a single iron ore powder or a sintering mixed material.

[0032] The method comprises the following steps: no less than 50 ml of water is placed in the sealed container, and the water does not contact the sample placed in the vessel or the sample placed in the sample bottle.

[0033] The invention is characterized in that: the relative humidity in the sealed container is not less than 99.5%.

[0034] Function and mechanism of the main process in the present invention

[0035] The reason why the present invention adds water until the samples with a particle size greater than 0.5 mm and a particle size ≤ 0.5 mm are immersed for not less than 48 hours is that the particle size of the pores inside the iron ore powder particles is relatively small. In order to ensure that the water fully fills the pores inside the particles, a sufficiently long immersion time must be ensured.

[0036] The reason why the present invention adopts the flat-laying method to determine the saturated moisture content of samples with a particle size greater than 0.5 mm, so that they enter the subsequent water absorption state within 5 minutes after being completely spread out without stacking, is that particles with a particle size greater than 0.5 mm are core particles and intermediate particles, and no extrusion state occurs after granulation. Therefore, the saturated capillary water absorbed by the particles in the flat-laying state without stacking is measured, and because the particles are placed for too long, the moisture in the particles will be evaporated.

[0037] The present invention loads two samples with the same weight of a particle size of ≤0.5 mm; one of the samples is loaded into a columnar container with a height scale, and the height H1 of the loaded sample is recorded as a comparison benchmark; the other sample is loaded in layers by extrusion and stacking, and when the material layer thickness is any fixed value of 4-5 mm per loading, a fixed external force and the same number of extrusions are used to repeatedly extrude the material layer, and after the loading of this sample, the height H2 of the loaded sample is recorded; when the ratio of H2 / H1 reaches 70-80% after extrusion, the subsequent water absorption state is entered within 5 minutes after the extrusion is stopped. This is because the extrusion degree of the iron ore powder particles after granulation is measured in an experimental manner and is within this range. In order to ensure the consistency of the measurement state with the particle state during granulation, the extrusion degree is limited to this range. In order to calculate the extrusion degree, two samples are loaded with the same weight, one sample loaded in a natural state is used as a comparison benchmark, and the other extruded sample is compared with it to calculate the extrusion degree.

[0038] The reason why the sample is made to absorb water to a saturated state and is carried out in a closed container together with the sample bottle or container containing the sample is that the numerical analysis of the liquid bridge model derived from the YANG-Laplace theorem shows that when the additional pressure of the curved liquid surface of the liquid bridge is a negative value, the water absorption does not reach saturation and the capillary force of the liquid bridge does not reach the maximum value. When the additional pressure is 0, the water absorption reaches saturation. When the additional pressure is a positive value, the water easily leaves the liquid bridge and moves freely between the particles to become gravity water, which has a destructive effect on granulation. Therefore, when the additional pressure is 0, that is, when the internal pressure of the curved liquid surface is equal to the saturated vapor pressure of the atmosphere, the amount of water absorbed between the particles is the saturated capillary water content. According to Kelvin's theorem: when the vapor pressure in the atmosphere is less than the curved liquid surface pressure, the water is transferred from the liquid surface to the atmosphere; when the vapor pressure in the atmosphere is greater than the curved liquid surface pressure, the water is transferred from the atmosphere to the liquid surface; when the vapor pressure in the atmosphere is equal to the liquid surface pressure, the liquid surface and the water in the atmosphere maintain a dynamic balance. Therefore, only when the vapor pressure in the atmosphere is the saturated vapor pressure can the water absorption between the particles reach the saturated capillary water state. The vapor pressure is the saturated vapor pressure, that is, the relative humidity in the atmosphere is 100%. Only in a closed container can the relative humidity of the atmosphere be ensured to reach a state close to 100%.

[0039] The reason why the present invention adopts formula (M +0.5mm *Q +0.5mm +M-0.5mm *Q -0.5mm ) / 100 is used to calculate the suitable moisture value of sintered granulated materials. Since the particles larger than 0.5 mm and the particles ≤ 0.5 mm have different existence states after granulation, they are divided into these two parts to measure their saturated capillary water and then add them up according to their proportions.

[0040] Compared with the prior art, the present invention does not require a large number of tests and linear regression model derivation. Through simple sample processing measurement and formula addition calculation, the moisture content suitable for sintering granulation can be obtained, providing more accurate guidance and services for on-site production. DETAILED DESCRIPTION

[0041] The present invention is described in detail below:

[0042] Example 1

[0043] Note: The raw material for sintering and granulation in this example is a single iron ore powder - Yangdi Mine Single Ore

[0044] A method for determining the moisture content of Yangdi ore suitable for granulation of sintering material, wherein the determination steps are:

[0045] 1) Prepare the sample

[0046] A. Obtaining samples: Obtain sample materials by taking samples from 5 points in total, and control the total amount of sample materials obtained to be 5000g;

[0047] B. Place the sample in an oven for drying at a temperature of 103°C for 3 hours until the moisture content is 0.01 wt%. Then weigh it and mark it as M. 总重 =4736.6g;

[0048] C. Screening: Take out the dried sample and screen it with a 0.5mm sieve to separate the samples into two particle sizes: one with a particle size greater than 0.5mm and one with a particle size ≤ 0.5mm. Mark and weigh them separately: M +0.5总重 =3184.4g, M -0.5总重 =1552.2g;

[0049] D. Calculate the weight percentage of the samples with particle size greater than 0.5 mm and particle size ≤ 0.5 mm, respectively, and record them as M +0.5mm wt% and M -0.5mm wt%; standby; M +0.5mm =M +0.5总重 ÷M 总重 *100wt%=67.23wt%,M -0.5mm wt%=M -0.5总重 ÷M 总重*100 wt% = 32.77 wt%;

[0050] E. Take 100g of the sample with a particle size greater than 0.5mm and 450g of the sample with a particle size ≤0.5mm, put them into containers respectively, add water until they are submerged, and soak them for 72 hours;

[0051] F. After taking out the samples, wipe off the moisture on the surface of the samples, and then use absorbent paper to test. Stop wiping when there is no trace of water absorption on the absorbent paper;

[0052] 2) Determine the saturated water content of the two particle size samples

[0053] A. The saturated water content of samples with a particle size greater than 0.5 mm is determined by the flat-laying method, that is, the sample is flatly laid on a glass sheet and made completely spread out without accumulation. After 3 minutes of placement, it enters the subsequent water absorption state;

[0054] B. For samples with a particle size of ≤0.5 mm, load two samples in the following way: one of them is loaded into a columnar container with a height scale by natural drop. When the sample is loaded to a height of H1, the weight of the loaded sample is recorded as 153.42 g, and H1 is controlled at 80 mm;

[0055] The other part is loaded by extrusion and stacking in layers. The sample with the same weight of 153.42g as the natural falling loading method is loaded in the following way. The thickness of the material layer is 4.5mm per loading. Then, the material layer is repeatedly extruded with an external force of 15N and the same extrusion times of 20 times. After this part of the sample is loaded, the height of the loaded sample H2=59.96mm is recorded; when the ratio of H2 / H1 reaches 74.95% after extrusion, the extrusion is stopped;

[0056] C. The sample absorbs water until it is saturated: Place the sample with a particle size greater than 0.5 mm after being flattened by the flattening method together with the glass sheet, and the sample with a particle size ≤ 0.5 mm after being squeezed and stacked together with the sample bottle into a sealed container; allow the sample to fully absorb the water in the space in the sealed container until it reaches a saturated state; place 51 ml of water in the sealed container;

[0057] Weighing of the sample when it reaches saturated water content: Take out the sample bottle and glass piece from the sealed container, and weigh the wet weight of the sample at this time. Samples with a particle size greater than 0.5 mm are marked as m 湿+0.5mm =61.19g, after extrusion and stacking, the particle size ≤0.5mm is marked as m 湿-0.5mm =175.13g;

[0058] D. Put the weighed wet sample into an oven for drying at 100°C for 2.5 hours until the moisture content is 0.01wt%. Take out the dried sample and weigh it respectively. Samples with a particle size greater than 0.5mm are marked as m. 干+0.5mm =55.51g, the sample with particle size ≤0.5mm is marked as m 干-0.5mm =152.07g;

[0059] E. Use the following formula to calculate the saturated capillary water content Q of the two samples with a particle size greater than 0.5 mm and a particle size ≤ 0.5 mm: The saturated capillary water content of the sample with a particle size greater than 0.5 mm is recorded as Q +0.5mm wt%, the saturated capillary water content of the sample with a particle size of ≤0.5 mm is recorded as Q- 0.5mm wt%;

[0060] Q=(m 湿 –m 干 ) / m 湿

[0061] Known m 湿+0.5mm =61.19g, m 湿-0.5mm =175.13g, m 干+0.5mm =55.51g,

[0062] m 干-0.5mm =152.07g, then:

[0063] Q +0.5mm wt%=(m 湿+0.5mm –m 干+0.5mm ) / m 湿+0.5mm =(61.19g–55.51g) / 61.19g=9.28wt%;

[0064] Q -0.5mm wt%=(m 湿-0.5mm –m 干-0.5mm ) / m 湿-0.5mm =(175.13g–152.07g) / 175.13g=13.17wt%;

[0065] 3) Calculation of suitable moisture value of Yangdi mine granulation materials:

[0066] Known M +0.5mm wt%=67.23wt%,M -0.5mm wt%=32.77wt%,

[0067] Q +0.5mm wt% = 9.28 wt%, Q -0.5mm wt% = 13.17wt%, and substituting it into the following formula, the result is

[0068] (M +0.5mm *Q +0.5mm +M -0.5mm *Q -0.5mm ) / 100=10.55wt%.

[0069] The suitable moisture value directly measured and calculated by this method is only 0.23wt% different from the optimal moisture value of 10.32wt% obtained by air permeability test after granulation test. The calculated value meets the production requirements.

[0070] Example 2

[0071] Note: The raw material for sintering and granulation in this embodiment is a single iron ore powder - Newton powder;

[0072] A method for determining the moisture content of sintering material suitable for granulation of new powder, wherein the determination steps are:

[0073] 1) Prepare the sample

[0074] A. Obtaining samples: Obtain sample materials by taking samples from 5 points in total, and control the total amount of sample materials obtained to be 4000g;

[0075] B. Place the sample in an oven for drying at a temperature of 106°C for 3 hours until the moisture content is 0.01 wt%. Then weigh it and mark it as M. 总重 =3758g;

[0076] C. Screening: Take out the dried sample and screen it with a 0.5mm sieve to separate the samples into two particle sizes: one with a particle size greater than 0.5mm and one with a particle size ≤ 0.5mm. Mark and weigh them separately: M +0.5总重 =2373.55g, M -0.5总重 =1384.45g;

[0077] D. Calculate the weight percentage of the samples with particle size greater than 0.5 mm and particle size ≤ 0.5 mm, respectively, and record them as M +0.5mm wt% and M -0.5mm wt%; standby; M +0.5mm =M +0.5总重 ÷M 总重 *100wt%=63.16wt%,M -0.5mm wt%=M -0.5总重 ÷M 总重 *100 wt% = 36.84 wt%;

[0078] E. Take 200g of the sample with a particle size greater than 0.5mm and 500g of the sample with a particle size ≤0.5mm, put them into containers respectively, add water until they are submerged, and soak them for 48 hours;

[0079] F. After taking out the samples, wipe off the moisture on the surface of the samples, and then use absorbent paper to test. Stop wiping when there is no trace of water absorption on the absorbent paper;

[0080] 2) Determine the saturated water content of the two particle size samples

[0081] A. The saturated water content of samples with a particle size greater than 0.5 mm is determined by the flat-laying method, that is, the sample is flatly laid on a flat-bottomed glass sheet with an edge, and is completely spread out without accumulation. After being left for 2.5 minutes, it enters the subsequent water absorption state;

[0082] B. For samples with a particle size of ≤0.5 mm, load two samples in the following way: one of them is loaded into a columnar container with a height scale by natural drop. When the sample is loaded to a height of H1, the weight of the loaded sample is recorded as 171.58 g, and H1 is controlled at 80 mm;

[0083] The other part is loaded by extrusion and stacking in layers. The sample with the same weight of 171.58g as the natural falling loading method is loaded in the following way. The thickness of the material layer is 4.0mm for each loading. Then, the material layer is repeatedly extruded with an external force of 14N and the same extrusion times of 20 times. After this part of the sample is loaded, the height of the loaded sample H2=62.16mm is recorded; when the ratio of H2 / H1 reaches 77.70% after extrusion, the extrusion is stopped;

[0084] C. The sample absorbs water until it is saturated: Place the sample with a particle size greater than 0.5 mm after being flattened by the flattening method together with the glass sheet, and the sample with a particle size ≤ 0.5 mm after being squeezed and stacked together with the sample bottle into a closed container; allow the sample to fully absorb the water in the space in the closed container until it reaches a saturated state; place 50 ml of water in the closed container;

[0085] Weighing of the sample when it reaches saturated water content: Take out the sample bottles containing the sample from the sealed container and weigh the wet weight of the sample at this time. The sample with a particle size greater than 0.5 mm is marked as m 湿+0.5mm =121.61g, after extrusion and stacking, the particle size ≤0.5mm is marked as m 湿-0.5mm =189.95g;

[0086] D. Put the weighed wet sample into an oven for drying at 100°C for 2.5 hours until the moisture content is 0.01wt%. Take out the dried sample and weigh it respectively. Samples with a particle size greater than 0.5mm are marked as m. 干+0.5mm =112.87g, the sample with particle size ≤0.5mm is marked as m 干-0.5mm =170.16g;

[0087] E. Use the following formula to calculate the saturated capillary water content Q of the two samples with particle size greater than 0.5 mm and particle size ≤ 0.5 mm:

[0088] The saturated capillary water content of the sample with a particle size greater than 0.5 mm is recorded as Q +0.5mm wt%, the saturated capillary water content of the sample with a particle size of ≤0.5 mm is recorded as Q- 0.5mm wt%;

[0089] Q=(m 湿 –m 干 ) / m 湿

[0090] Known m 湿+0.5mm =121.61g, m 湿-0.5mm =189.95g, m 干+0.5mm =112.87g,

[0091] m 干-0.5mm =170.16g, then:

[0092] Q +0.5mm wt%=(m 湿+0.5mm –m 干+0.5mm ) / m 湿+0.5mm =(121.61g–112.87g) / 121.61g=7.19wt%;

[0093] Q -0.5mm wt%=(m 湿-0.5mm –m 干-0.5mm ) / m 湿-0.5mm =(189.95g–170.16g) / 189.95g=10.42wt%;

[0094] 3) Calculation of suitable moisture value of new powder granulation materials:

[0095] Known M +0.5mm wt%=63.16wt%,M -0.5mm wt%=36.84wt%,

[0096] Q +0.5mm wt% = 7.19 wt%, Q -0.5mm wt% = 10.42wt%, and substituting it into the following formula, the calculated result is

[0097] (M +0.5mm *Q +0.5mm +M -0.5mm *Q -0.5mm ) / 100=8.34wt%.

[0098] The suitable moisture value directly measured and calculated by this method is only 0.13wt% different from the optimal moisture value of 8.21wt% obtained by air permeability test after granulation test, and the calculated value meets the production requirements.

[0099] Example 3

[0100] Note: The raw material for sintering and granulating in this embodiment is sintering mixed material

[0101] A method for determining the moisture content of a sintering material suitable for granulation as a sintering mixture, wherein the determination steps are:

[0102] 1) Prepare the sample

[0103] A. Obtaining samples: Obtain sample materials by taking samples from 5 points in total, and control the total amount of sample materials obtained to be 4700g;

[0104] B. Place the sample in an oven for drying at a temperature of 105°C for 3 hours until the moisture content is 0.01wt%. Then weigh the weight and mark it as M. 总重 =4501.66g;

[0105] C. Screening: Take out the dried sample and screen it with a 0.5mm sieve to separate the samples into two particle sizes: one with a particle size greater than 0.5mm and one with a particle size ≤ 0.5mm. Mark and weigh them separately: M +0.5总重 =2917.98g, M -0.5总重 =1583.68g;

[0106] D. Calculate the weight percentage of the samples with particle size greater than 0.5 mm and particle size ≤ 0.5 mm, respectively, and record them as M +0.5mm wt% and M -0.5mm wt%; standby; M +0.5mm =M +0.5总重 ÷M 总重 *100wt%=64.82wt%,M -0.5mm wt%=M -0.5总重 ÷M 总重 *100 wt% = 35.18 wt%;

[0107] E. Take 80g of the sample with a particle size greater than 0.5mm and 410g of the sample with a particle size ≤0.5mm and put them into containers respectively, add water until they are submerged, and soak them for 72 hours;

[0108] F. After taking out the samples, wipe off the moisture on the surface of the samples, and then use absorbent paper to test. Stop wiping when there is no trace of water absorption on the absorbent paper;

[0109] 2) Determine the saturated water content of the two particle size samples

[0110] A. The saturated water content of samples with a particle size greater than 0.5 mm is determined by the flat-laying method, that is, the sample is flatly laid on a glass sheet and made completely spread out without accumulation. After 4 minutes of placement, it enters the subsequent water absorption state;

[0111] B. For samples with a particle size of ≤0.5 mm, load two samples in the following way: one of them is loaded into a columnar container with a height scale by natural drop. When the sample is loaded to a height of H1, the weight of the loaded sample is recorded as 141.57 g, and H1 is controlled at 80 mm;

[0112] The other part is loaded by extrusion and stacking in layers. The sample with the same weight of 141.57g as the natural falling loading method is loaded in the following way. The thickness of the material layer is 4.5mm per loading. Then, the material layer is repeatedly extruded with an external force of 14N and the same number of extrusions for 24 times. After this part of the sample is loaded, the height of the loaded sample H2=61.02mm is recorded; when the ratio of H2 / H1 reaches 76.28% after extrusion, the extrusion is stopped;

[0113] C. The sample absorbs water until it is saturated: Place the sample with a particle size greater than 0.5 mm after being flattened by the flattening method together with the glass sheet, and the sample with a particle size ≤ 0.5 mm after being squeezed and stacked together with the sample bottle into a closed container; allow the sample to fully absorb the water in the space in the closed container until it reaches a saturated state; place 52 ml of water in the closed container;

[0114] Weighing of the sample when it reaches saturated water content: Take out the sample bottles containing the sample from the sealed container and weigh the wet weight of the sample at this time. The sample with a particle size greater than 0.5 mm is marked as m 湿+0.5mm =34.17g, after extrusion and stacking, the particle size ≤0.5mm is marked as m 湿-0.5mm =152.88g;

[0115] D. Put the weighed wet sample into an oven for drying at 100°C for 2.5 hours until the moisture content is 0.01wt%; take out the dried sample and weigh it; the particle size is greater than

[0116] The mark of 0.5mm sample is m 干+0.5mm =32.06g, the sample with particle size ≤0.5mm is marked as m 干-0.5mm =140.53g; E. Use the following formula to calculate the saturated capillary water content Q of the two samples with a particle size greater than 0.5mm and a particle size ≤0.5mm:

[0117] The saturated capillary water content of the sample with a particle size greater than 0.5 mm is recorded as Q +0.5mmwt%, saturation of sample with particle size ≤ 0.5 mm

[0118] Capillary water content is recorded as Q- 0.5mm wt%;

[0119] Q=(m 湿 –m 干 ) / m 湿

[0120] Known m 湿+0.5mm =34.17 g, m 湿-0.5mm =152.88g, m 干+0.5mm =32.06g,

[0121] m 干-0.5mm =140.53g, then:

[0122] Q +0.5mm wt%=(m 湿+0.5mm –m 干+0.5mm ) / m 湿+0.5mm =(34.17g–32.06g) / 34.17g=6.18wt%;

[0123] Q -0.5mm wt%=(m 湿-0.5mm –m 干-0.5mm ) / m 湿-0.5mm =(152.88g–140.53g) / 152.88g=8.08wt%;

[0124] 3) Calculation of suitable moisture value of sintering mixture granulation material:

[0125] Known M +0.5mm wt%=64.82wt%,M -0.5mm wt%=35.18wt%,

[0126] Q +0.5mm wt% = 6.18 wt%, Q -0.5mm wt% = 8.08wt%, and substituting it into the following formula, the calculated result is

[0127] (M +0.5mm *Q +0.5mm +M -0.5mm *Q -0.5mm ) / 100=6.85wt%.

[0128] The suitable moisture value directly measured and calculated by this method is only 0.06wt% different from the optimal moisture value of 6.91wt% obtained by air permeability test after granulation test, and the calculated value meets the production requirements.

[0129] This specific implementation is only the best example and is not a restrictive implementation of the technical solution of the present invention.

Claims

1. A method for determining the moisture content of sintering material suitable for granulation, characterized in that: The measurement steps are: 1) Prepare the sample A. Obtaining samples: Use a uniform multi-point sampling method to obtain sample materials, and control the total amount of sample materials obtained to be no less than 3000g; B. Place the sample in an oven for drying, control the drying temperature to be no less than 100°C, and the drying time to be no less than 2 hours, until the moisture content is ≤0.05wt%; then weigh the weight and mark it as M. 总重 ; C. Screening: Take out the dried sample and screen it with a 0.5mm sieve to screen out two kinds of particle size samples: one with a particle size greater than 0.5mm and one with a particle size ≤0.5mm; and mark them as M respectively. +0.5总重 and M -0.5总重 ; D. Calculate the weight percentage of the samples with particle size greater than 0.5 mm and particle size ≤ 0.5 mm, respectively, and record them as M +0.5mm wt% and M -0.5mm wt%;M +0.5mm wt%=M +0.5总重 ÷M 总重 *100 wt%, M -0.5mm wt%=M -0.5总重 ÷M 总重 *100 wt%; E. Soak the samples with particle size greater than 0.5mm and ≤0.5mm separately: take a weight of not less than 50g for the sample with particle size greater than 0.5mm and take a weight of not less than 400g for the sample with particle size ≤0.5mm, put them into containers respectively, add water until they are submerged, and soak for not less than 48 hours; F. After taking out the samples, wipe off the moisture on the surface of the samples, and then use absorbent paper to test. Stop wiping when there is no trace of water absorption on the absorbent paper; 2) Determine the saturated water content of the two particle size samples A. The saturated water content of samples with a particle size greater than 0.5 mm is determined by the flat spreading method, that is, the sample is spread flat on the container and allowed to enter the subsequent water absorption state within 5 minutes after it is completely spread out without accumulation; B. For samples with a particle size of ≤0.5mm, place two samples in the following manner: one of them is placed in a columnar container with a height scale by natural drop. When the sample is placed to a height of H1, the weight of the sample is recorded. H1 is controlled between 50 and 100mm. The other is to load the sample by extrusion and stacking in layers. The sample with the same weight as the natural falling loading method is loaded in the following way. When the material layer is any fixed value of 4-5mm thickness, a fixed external force and the same number of extrusions are used to extrude the material layer. After the sample is loaded, the height H2 of the loaded sample is recorded; when the ratio of H2 / H1 reaches 70-80% after extrusion, the subsequent water absorption state is entered within 5 minutes after stopping extrusion; C. The sample absorbs water until it is saturated: Place the sample with a particle size greater than 0.5 mm after being flattened by the flattening method together with the vessel, and the sample with a particle size ≤ 0.5 mm after being squeezed and stacked together with the sample bottle into a closed container; allow the sample to fully absorb the water in the space in the closed container until it reaches a saturated state; Weighing of the sample when it reaches saturated water content: Take out the sample bottles containing the sample from the sealed container and weigh the wet weight of the sample at this time. Samples with a particle size greater than 0.5 mm are marked as m 湿+0.5mm After extrusion and stacking, the sample with a particle size of ≤0.5mm is marked as m 湿-0.5mm ; D. Put the weighed wet sample into an oven for drying at a temperature not lower than 100°C for at least 2 hours until the moisture content does not exceed 0.05wt%. Take out the dried sample and weigh it respectively. Samples with a particle size greater than 0.5mm are marked as m. 干+0.5mm , the sample with particle size ≤ 0.5 mm is marked as m 干-0.5mm ; E. Use the following formula to calculate the saturated capillary water content Q of the two samples with a particle size greater than 0.5 mm and a particle size ≤ 0.5 mm: The saturated capillary water content of the sample with a particle size greater than 0.5 mm is recorded as Q +0.5mm wt%, the saturated capillary water content of the sample with a particle size of ≤0.5 mm is recorded as Q- 0.5mm wt%; Q=(m 湿 –m 干 ) / m 湿 Where: m 湿 —It indicates the weight of the sample with a particle size greater than 0.5 mm or a particle size ≤ 0.5 mm after absorbing the water in the space of the closed container until it reaches a saturated state and no longer changes, in g; m 干 —Indicates the weight of the sample after drying for a particle size greater than 0.5 mm or a particle size ≤ 0.5 mm, in g; 3) Calculation of the moisture content of the granulated object to be tested, the calculation formula is: (M +0.5mm *Q +0.5mm +M -0.5mm *Q -0.5mm ) / 100 Where: M +0.5mm —Indicates the weight percentage of the sample with a particle size greater than 0.5 mm after screening, in wt%; M -0.5mm —Indicates the weight percentage of the sample with a particle size of ≤0.5mm after screening, in wt%; Q +0.5mm —Indicates the saturated capillary water content of the sample with a particle size greater than 0.5 mm, in wt%; Q -0.5mm —Indicates the saturated capillary water content of the sample with a particle size of ≤0.5mm, in wt%.

2. A method for determining the moisture content of sintering material suitable for granulation as claimed in claim 1, characterized in that: The sintering material is a single iron ore powder or a sintering mixed material.

3. A method for determining the moisture content of sintering material suitable for granulation according to claim 1, characterized in that: No less than 50 ml of water is placed in the sealed container, and the water does not contact the sample placed in the vessel or the sample placed in the sample bottle.

4. A method for determining the moisture content of sintering material suitable for granulation as claimed in claim 1, characterized in that: The relative humidity in the sealed container is not less than 99.5%.