Limestone burst characteristic combination identification method

Abstract

The invention relates to a limestone burst characteristic combination identification method. The method comprises a roasting test, an electron microscope detection method and a volume density detection method. Firstly, explosive limestone and non-explosive limestone are preliminarily determined through a roasting test, on the basis of the preliminary determination, the size, the composition and the distribution mode of limestone crystals are detected through an electron microscope detection method to further confirm the burst characteristics of the limestone, and finally, the explosive limestone and the non-explosive limestone are determined again through a volume density detection method. Due to the fact that the explosive limestone is large in crystal and obvious in heterogeneity of components, such as dolomitic calcium carbonate, the porosity of the explosive limestone is large, and the density of the explosive limestone is lower than that of non-explosive limestone. The three methods are combined for screening, field acceptance is effectively guided, the process parameters of the rotary kiln are correspondingly adjusted according to the division of the burst grades, and the adverse effect of outsourcing mineral aggregates on the process of the rotary kiln is reduced to the minimum.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgical lime mineral processing, and in particular to a combined identification method for limestone bursting characteristics. Background Art

[0002] At present, existing detection technologies are mainly focused on the detection of physical and chemical components, such as calcium oxide content, sulfur dioxide and other chemical components. The roasting characteristics of limestone entering the kiln cannot be identified and determined during the acceptance of raw materials entering the factory, resulting in lax acceptance inspection, which brings difficulties to process adjustment and affects the quality of output lime and production capacity release.

[0003] The purpose of the present invention is: 1. To form a combined identification method of limestone roasting characteristics that can be identified on site to guide on-site quality acceptance. 2. To form a critical standard for matching roasting characteristics with rotary kiln process to guide on-site process operation. Summary of the invention

[0004] The purpose of the present invention is to provide a method for identifying the combination of limestone bursting characteristics in view of the above problems.

[0005] The object of the present invention is achieved as follows: A combined identification method for limestone bursting characteristics, comprising: (1) limestone bursting characteristics detection method 1: roasting test: during the on-site acceptance process, 50 samples of 20-40 mm are taken and sent to the testing room for roasting test. The temperature during the roasting test is controlled in the range of 300-900°C and roasted for 10-30 minutes. By observing the bursting, collapse, longitudinal cracking, and fragile stone quality of the material during the heating process in the range of 300-900°C, a comparison analysis is performed with the original sample to form an appearance identification method; (2) limestone bursting characteristics detection method 2: electron microscope detection method: through the electron microscope The image of the microscope is used for observation and judgment. The magnification of the electron microscope is 500 to 5000 times; (3) Limestone bursting characteristic detection method three: Limestone volume density detection method: The density of limestone is measured by a balance and a measuring cylinder. The mass of limestone is measured by a balance in its natural state to obtain M; when the volume of limestone is measured by a measuring cylinder, the sample should be wax-sealed, and then the volume of limestone is measured by the displacement method as V1-V2-V3, where V1 is the volume of the measuring cylinder after the sample is placed, V2 is the volume of the measuring cylinder before the sample is placed, and V3 is the volume of the wax. The volume density of limestone = M / (V1-V2-V3).

[0006] Limestone roasting characteristics test method 1, limestone bursting characteristics test method 2 and limestone bursting characteristics test method 3 are used for joint identification. Method 1 standard: when bursting ≤20%, collapse ratio ≤20%, longitudinal crack ratio ≤30% occurs in the roasting test, then method 2 and method 3 are carried out; method 2 standard: bulk density <2.7g / cm 3 Unqualified, body density ≥ 2.7g / cm3 Qualified when method three standard: unqualified when dolomitized calcium carbonate is found in the electron microscope, qualified when there is no dolomitized calcium carbonate in the electron microscope; among the three test methods, when bursting occurs in the limestone roasting characteristic detection method one, the limestone bursting characteristic detection method two and the limestone bursting characteristic detection method three are not carried out, and it is directly determined that it is strictly forbidden to add material. If the limestone roasting characteristic detection method one is qualified, then the limestone bursting characteristic detection method two and the limestone bursting characteristic detection method three are carried out. If two of the three items are unqualified, it is strictly forbidden to add material. If one of the three methods is unqualified, the rotary kiln process parameters are adjusted accordingly based on the severity of the bursting in the roasting test.

[0007] The classification of bursting grades corresponds to the adjustment of rotary kiln process parameters as follows: when collapsing: kiln tail temperature: 1050±75℃, kiln head temperature: 600℃-700℃, ID fan speed: ≤92%, set output: 800-1170d / t, set coal quantity: ≤9500kg / h, roasting rate: 94±1%, dust removal inlet temperature: ≤225℃, mill inlet temperature: 250℃-285℃, mill outlet temperature: ≤70℃, ash discharge temperature: ≤120℃; when longitudinal cracking: kiln tail temperature: 1050±75℃, kiln head temperature: 680℃-780℃, ID fan speed: ≤92%, set output: 800- 1170d / t, set coal quantity: ≤9500kg / h, roasting rate: 96±1%, dust removal inlet temperature: ≤225℃, mill inlet temperature: 250℃-285℃, mill outlet temperature: ≤70℃, ash discharge temperature: ≤120℃; when small cracks: kiln tail temperature: 1050±75℃, kiln head temperature: 880℃-1030℃, ID fan speed: ≤95%, set output: 850-1050d / t, set coal quantity: ≤9500kg / h, roasting rate: 100%, dust removal inlet temperature: ≤225℃, mill inlet temperature: 250℃-285℃, mill outlet temperature: ≤70℃, ash discharge temperature: ≤120℃.

[0008] The beneficial effects of the present invention are: through the joint identification of three methods, the on-site acceptance is effectively guided, and the adverse effects of purchased mineral materials on the rotary kiln process are minimized. Through nearly a year of research and on-site practice, the units using purchased limestone have formed a unique process operation method for changes in multiple suppliers, such as the classification of rotary kiln conditions, the setting and on-site tracking of key process indicators, the process for handling objections to the quality of purchased limestone entering the kiln, the switching standards for low-carbon, primary, and secondary lime roasting processes, and the process for handling changes in environmental protection indicators. The implementation of a series of methods and processes has formed a complete set of closed-loop management, and the rotary kiln conditions are adjustable and controllable, which effectively guarantees large-scale production operations, mainly reflected in the release of production capacity, environmental protection compliance, and stable quality, so that the rotary kiln can operate stably and with high quality throughout the year. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The present invention will be further described below in conjunction with the accompanying drawings.

[0010] Figure 1 This is a 2000-fold electron microscope image of the non-explosive limestone of the present invention.

[0011] Figure 2 It is a 2000-fold electron microscope image of the explosive limestone of the present invention.

[0012] Figure 3 It is a 5000-fold electron microscope image of the non-explosive limestone of the present invention.

[0013] Figure 4 It is a 5000-fold electron microscope image of the explosive limestone of the present invention.

[0014] Figure 5 This is a graph showing the density test results for non-explosive limestone and explosive limestone.

[0015] In the figure: 1 Crystals of non-explosive limestone, 2 Dolomitized calcium carbonate of explosive limestone, 3 Crystals of explosive limestone. DETAILED DESCRIPTION

[0016] Limestone, due to its different formation ages, has different physical and mechanical properties. The limestone from external suppliers is mainly mixed with limestone mines of the Upper Majiagou Formation, Lower Majiagou Formation, and Section 1 of the Fengfeng Formation in the Ordovician. It is mainly composed of calcite, a small amount of quartz and dolomite. The joints and fissures of the ore layers are well developed, and the compressive strength of parallel bedding is relatively low. It may burst during the roasting process. Under the existing acceptance methods, it is impossible to distinguish it from the limestone mine of Section 2 of the Fengfeng Formation through visual inspection and simple testing. Now a combined identification method is adopted to solve the problem of on-site acceptance of limestone that has troubled the industry for many years more accurately, quickly and effectively. Through research and field practice, we first introduced one of the methods for detecting the bursting characteristics of limestone: the roasting test. That is, during the on-site acceptance process, we took an appropriate amount of samples and sent them to the testing room for a roasting test. The test temperature was controlled between 600-900 degrees Celsius and the roasting time was 10-30 minutes. By observing the bursting, collapse, longitudinal cracks and small cracks of the material in different temperature ranges, and comparing and analyzing them with the original sample, we formed an appearance judgment method to guide rapid on-site acceptance.

[0017] Secondly, we introduce one of the methods for testing the bursting characteristics of limestone: the electron microscope test method, that is, during the on-site acceptance process, take a suitable amount of representative samples, hammer them to form a natural cross section, and observe the size, composition and distribution of the crystals through the electron microscope image. If the crystals are of the same size and distributed in parallel, a method of appearance identification is formed to guide the rapid on-site acceptance. Limestone samples from different sources and two groups of limestone produced by rotary kiln roasting are sampled and sent for inspection. The samples are magnified 500 to 5000 times using an electron microscope to observe the crystal size and distribution ( Figure 2 and 3 Electron microscope images of non-explosive limestone and explosive limestone). As can be seen from the figure, the explosive limestone has larger crystals than the non-explosive limestone; the composition of the non-explosive limestone is relatively balanced, without obvious impurities and impurity erosion; the composition of the explosive limestone is obviously heterogeneous, and after EDS testing, it is found to be dolomitized calcium carbonate. From the figure, it can be concluded that the explosive lime crystals are twice as many as the non-explosive lime crystals ( Figure 3 and 4 Electron microscope image of non-explosive lime and explosive lime).

[0018] Finally, one of the methods for testing the explosion characteristics of limestone is introduced: the limestone bulk density test method. Bulk density refers to the mass per unit volume in a state that includes solid volume, openings, and closed pores. Limestone bulk density test method: The density of limestone is measured by a balance and a measuring cylinder. The mass of limestone is measured by a balance in its natural state (i.e., in a dry state stored in the air for a long time) (M); when measuring the volume of limestone with a measuring cylinder, the sample should be wax-sealed, and then the volume of limestone is measured by the drainage method (V1-V2-V3, where V1 is the volume of the measuring cylinder after the sample is placed, V2 is the volume of the measuring cylinder before the sample is placed, and V3 is the volume of wax). The bulk density of limestone = M / (V1-V2-V3). In building materials, bulk density is used to describe the ratio of the mass and volume of a material. Through experiments, it was found that the bulk density of explosive limestone is less than that of non-explosive limestone. The crystals of explosive limestone are large and the composition is obviously heterogeneous. For example, the crystals of dolomitized calcium carbonate are twice as large as those of non-explosive limestone. As a result, the porosity of explosive limestone is larger and the density is lower than that of non-explosive limestone. During the on-site acceptance process, an appropriate amount of samples are taken and sent to the testing room for bulk density testing. After comparison with non-explosive stone, a significant difference discrimination method is formed. It is found that the bulk density of explosive limestone is less than that of non-explosive limestone ( Figure 5 Density test results of non-explosive limestone and explosive limestone).

[0019] The three methods are used for joint identification. If two or more of the three items meet the conditions, it is strictly forbidden to add materials. If one of the three items meets the conditions, the rotary kiln process parameters are adjusted accordingly according to the classification of bursting grades to minimize the adverse effects of purchased ore on the rotary kiln process.

[0020] Limestone roasting characteristics test method 1, limestone bursting characteristics test method 2 and limestone bursting characteristics test method 3 are used for joint identification. Method 1 standard: when bursting ≤20%, collapse ratio ≤20%, longitudinal crack ratio ≤30% occurs in the roasting test, then method 2 and method 3 are carried out; method 2 standard: bulk density <2.7g / cm 3 Method 3 standard: if there is dolomitized calcium carbonate in the electron microscope, it is unqualified. Among the three test methods, when bursting occurs in the roasting test, the bulk density and electron microscope test can be omitted, and it is directly determined that it is strictly forbidden to add materials. If no bursting occurs in the roasting test, the bulk density and electron microscope test are required. If two of the above conditions are met, it is strictly forbidden to add materials. If one of the three methods meets the above conditions, the rotary kiln process parameters are adjusted accordingly based on the severity of the bursting in the roasting test.

[0021] Explosion refers to the sudden breakage and violent explosion of limestone during the heating process, turning the limestone into small pieces and powder.

[0022] Longitudinal cracking refers to the phenomenon that limestone splits in a direction parallel to its axis and runs vertically and horizontally during the heating process.

[0023] Small cracks refer to the phenomenon that limestone splits along the direction parallel to its body axis but does not penetrate during the heating process.

[0024] Collapse refers to the phenomenon that limestone suddenly cracks during the heating process, and the lime blocks become small pieces without powder.

[0025] From March to July 2024, it was implemented at the Dongshan crushing and collecting site. After verification by large-scale roasting tests in rotary kilns, the results were good. A limestone bursting test method was formed, the on-site acceptance rules were re-established, and the rotary kiln process technology operating procedures were compiled.

[0026] 1. On-site acceptance rules: When handing over each shift, the person in charge will use a random number generator to generate a random vehicle number, and sample according to the number according to the acceptance rules. The small samples of the shift will be combined into large samples, which will be reduced and then formed into test samples for inspection.

[0027] 2. Limestone burst determination steps: 1. Select 50 limestone samples with a diameter of 20-40 mm at room temperature, put them into a preheated muffle furnace, control the test temperature between 600-900 degrees, roast for 10-30 minutes, record the specific burst temperature, heat to 950 degrees and keep warm for 2 hours before taking out, record the number of limestone defective blocks that burst as the numerator, and the burst rate is equal to the number of defective blocks divided by 50 multiplied by 100%. There are four levels of burst, burst, collapse, longitudinal crack, and small crack. Statistical calculation and analysis are performed separately.

[0028] 2. If bursting occurs during the roasting test, bulk density detection and electron microscope observation are required; if bursting does not occur, bulk density detection and electron microscope observation are not required, and then the rotary kiln process parameters are adjusted accordingly according to the classification of bursting grades.

[0029] 3. The verification results of the rotary kiln process test: ⑴ The limestone with bursting will be returned on site regardless of its bursting ratio and will not be allowed to enter the kiln. The bursting ratio of collapsing is less than 30%, and it can be used in the kiln. The bursting ratio of longitudinal cracking is less than 20%, and it can be used in the kiln. Small cracks are acceptable. ⑵ According to the classification of collapsing, longitudinal cracking and small cracking, different limestone process parameters are corresponding.

[0030]

[0031] The above description is only a specific embodiment of the present invention, but the structural features of the protection scope of the present invention are not limited thereto. Any changes or modifications made by any technician in the field of the present invention are all covered by the patent scope of the present invention.

Claims

1. A combined identification method for limestone bursting characteristics, characterized in that: include: (1) Limestone bursting characteristics detection method 1: roasting test: during the on-site acceptance process, 50 samples of 20-40 mm are taken and sent to the testing room for roasting test. The temperature during the roasting test is controlled in the range of 300-900℃ and roasted for 10-30 minutes. By observing the bursting, collapse, longitudinal cracking, and fragile stone in the process of heating in the range of 300-900℃, a comparison analysis is formed with the original sample to form an appearance identification method; (2) Limestone bursting characteristics detection method 2: Electron microscope detection method: Observe and judge through the mirror image of the electron microscope, the magnification of the electron microscope is 500 to 5000 times; (3) Limestone bursting characteristics detection method three: Limestone volume density detection method: The density of limestone is measured by a balance and a measuring cylinder. The mass of limestone is measured by a balance in its natural state to obtain M. When the volume of limestone is measured by a measuring cylinder, the sample should be wax-sealed, and then the volume of limestone is measured by the displacement method as V1-V2-V3, where V1 is the volume of the measuring cylinder after the sample is placed, V2 is the volume of the measuring cylinder before the sample is placed, and V3 is the volume of wax. The volume density of limestone = M / (V1-V2-V3).

2. A limestone bursting characteristic combination identification method according to claim 1, characterized in that: Limestone roasting characteristics test method 1, limestone bursting characteristics test method 2 and limestone bursting characteristics test method 3 are used for joint identification. Method 1 standard: when bursting ≤20%, collapse ratio ≤20%, longitudinal crack ratio ≤30% occurs in the roasting test, then method 2 and method 3 are carried out; method 2 standard: bulk density <2.7g / cm 3 Unqualified, body density ≥ 2.7g / cm 3 Qualified when method three standard: unqualified when dolomitized calcium carbonate is found in the electron microscope, qualified when there is no dolomitized calcium carbonate in the electron microscope; among the three test methods, when bursting occurs in the limestone roasting characteristic detection method one, the limestone bursting characteristic detection method two and the limestone bursting characteristic detection method three are not carried out, and it is directly determined that it is strictly forbidden to add material. If the limestone roasting characteristic detection method one is qualified, then the limestone bursting characteristic detection method two and the limestone bursting characteristic detection method three are carried out. If two of the three items are unqualified, it is strictly forbidden to add material. If one of the three methods is unqualified, the rotary kiln process parameters are adjusted accordingly based on the severity of the bursting in the roasting test.

3. A limestone bursting characteristic combination identification method according to claim 2, characterized in that: The classification of bursting grades corresponds to the adjustment of rotary kiln process parameters as follows: when collapsing: kiln tail temperature: 1050±75℃, kiln head temperature: 600℃-700℃, ID fan speed: ≤92%, set output: 800-1170d / t, set coal quantity: ≤9500kg / h, roasting rate: 94±1%, dust removal inlet temperature: ≤225℃, mill inlet temperature: 250℃-285℃, mill outlet temperature: ≤70℃, ash discharge temperature: ≤120℃; when longitudinal cracking: kiln tail temperature: 1050±75℃, kiln head temperature: 680℃-780℃, ID fan speed: ≤92%, set output: 800- 1170d / t, set coal quantity: ≤9500kg / h, roasting rate: 96±1%, dust removal inlet temperature: ≤225℃, mill inlet temperature: 250℃-285℃, mill outlet temperature: ≤70℃, ash discharge temperature: ≤120℃; when small cracks: kiln tail temperature: 1050±75℃, kiln head temperature: 880℃-1030℃, ID fan speed: ≤95%, set output: 850-1050d / t, set coal quantity: ≤9500kg / h, roasting rate: 100%, dust removal inlet temperature: ≤225℃, mill inlet temperature: 250℃-285℃, mill outlet temperature: ≤70℃, ash discharge temperature: ≤120℃.

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