Method for comprehensively evaluating quality performance of bentonite and binder for pellets

Abstract

The invention discloses a comprehensive evaluation method for quality performance of bentonite and a binder for pellets, and belongs to the technical field of quality performance analysis of bentonite and a binder. Comprising the following steps: (1) selecting bentonite or a binder to be evaluated, and matching with concentrate as a standard raw material; (2) manufacturing green pellets by adopting a laboratory pelletizing disc; (3) controlling the time for preparing the green pellets to be within 21min; (4) measuring the drop strength of the green pellets, and recording the lowest binder ratio meeting the strength requirement when the drop strength is required to be more than or equal to 5 times per pellet; (5) preparing finished pellets from the green pellets meeting the drop strength; and (6) detecting the compressive strength and TFe and SiO2 chemical components of the finished pellets, wherein the higher the compressive strength is, the higher the grade is, and the better the quality performance of the bentonite and the binder is. The invention aims to provide a method for comprehensively evaluating the quality performance of bentonite and a binder for pellets, and solves the problem that the performance of the binder is incomprehensively evaluated by a traditional method.

Description

Technical Field

[0001] The invention belongs to the technical field of bentonite and binder quality performance analysis, and in particular relates to a comprehensive evaluation method for the quality performance of bentonite and binder for pelletizing. Background Art

[0002] As the core raw material of blast furnace "fine material", the quality of pellets directly affects the blast furnace smelting efficiency and environmental protection level. Bentonite and binder are key auxiliary materials in pellet production. Their performance determines the strength of green balls, the grade of finished ore and metallurgical properties. The traditional evaluation method of bentonite and binder uses colloidal value and expansion index as core indicators, but there are two defects: (1) Colloidal value and expansion index cannot accurately reflect the compatibility of binders with different iron materials (such as iron concentrates with different particle size and specific surface area), resulting in the selection of proportions in industrial applications relying on experience, which is prone to excessive binder, reducing the iron grade of pellets and worsening high-temperature metallurgical properties; (2) The dynamic effect of green ball composition on drop strength and the synergistic effect of finished ball compressive strength and chemical composition are not systematically considered. The evaluation system is single and difficult to guide actual production optimization.

[0003] Furthermore, existing methods lack standardized raw materials and process parameters, resulting in poor comparability of test data for different iron materials, making it impossible to develop a universal evaluation standard. For example, while Baosteel attempted to adjust the binder type in pellet production, frequent fluctuations in iron materials prevented the establishment of a compatibility evaluation system, leading to frequent fluctuations in pellet quality. Therefore, a comprehensive evaluation method for the quality and performance of bentonite and binders used in pelletizing is urgently needed. Summary of the Invention

[0004] The purpose of the present invention is to provide a comprehensive evaluation method for the quality and performance of bentonite and a binder for pelletizing, so as to solve the problem that the traditional method is not comprehensive in evaluating the performance of the binder.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] The present invention provides a comprehensive evaluation method for the quality and performance of bentonite and a binder for pelletizing, comprising the following steps:

[0007] (1) Select the bentonite or binder to be evaluated and match it with the concentrate as the standard raw material;

[0008] (2) The standard raw materials in step (1) are used to make green balls using a laboratory ball making tray, and the moisture content of the ball making process is controlled to 8.0% ± 0.5%;

[0009] (3) The time for preparing the balls in step (2) is controlled within 21 minutes, wherein the time for preparing the mother balls is 2.8-3.2 minutes, the time for growing the balls is 7-9 minutes, and the time for compacting the balls is 8-12 minutes;

[0010] (4) Determine the drop strength of the green balls in step (3), requiring it to reach ≥5 times / ball, and record the lowest binder ratio that meets the strength requirement. The lower the ratio, the better the performance.

[0011] (5) preparing finished balls from the green balls that meet the drop strength in step (4), with a drying temperature of 170-190°C and a time of 28-32 min; a preheating temperature of 850-950°C and a time of 8-12 min; and a roasting temperature of 120-01300°C and a time of 8-12 min;

[0012] (6) The compressive strength and chemical composition of TFe and SiO2 of the finished balls in step (5) are tested. The higher the compressive strength and the higher the grade, the better the quality and performance of the bentonite and the binder.

[0013] Furthermore, the concentrate is matched with a specific surface area of 1500cm 2 / g, iron concentrate with a spheroidization index ≥0.25.

[0014] Furthermore, the laboratory pelletizing disk has a diameter of φ=1000 mm.

[0015] Furthermore, the mother ball preparation time is 3 minutes, the green ball growth time is 8 minutes, and the green ball compaction time is 10 minutes.

[0016] Furthermore, the drying stage temperature is 180° C. and the time is 30 min.

[0017] Furthermore, the preheating temperature is 900°C and the time is 10 minutes.

[0018] Furthermore, the calcination temperature is 1240° C. and the time is 10 min.

[0019] Compared with the prior art, the present invention has the following beneficial technical effects:

[0020] The present invention provides a comprehensive evaluation method based on the falling strength of green balls, the compressive strength of finished balls and the chemical composition as core indicators, which solves the problem that the traditional method is not comprehensive in evaluating the performance of binders. DETAILED DESCRIPTION

[0021] The technical solution of the present invention is described in detail below in conjunction with the embodiments.

[0022] In the embodiment of the present invention, Baotou Steel Pipeline Concentrate is selected as the unified concentrate, and its composition and basic properties are shown in Table 1 and Table 2 respectively. The binders to be tested are belt bentonite, Guyang bentonite and composite binder QNP-8, and the composition attributes and physical and chemical properties of each binder are shown in Table 3. The ratio of each binder to pipeline concentrate and the drop strength of the green ball are shown in Table 4. The green balls prepared with each binder and pipeline concentrate are used to prepare finished balls. The drying section temperature is 180°C and the time is 30min; the preheating section temperature is 900°C and the time is 10min; the roasting temperature is 1240°C and the time is 10min. The grade and compressive strength of the prepared finished ductile iron are shown in Table 5. Based on the comprehensive ratio, the grade of the finished ductile iron and the compressive strength, Guyang bentonite is determined to be the best choice for this ore. It can be seen that the present invention realizes accurate evaluation of binder adaptability through standardized raw material selection and multi-index detection of green balls and finished balls.

[0023] Table 1 Chemical composition of pipeline concentrate, %

[0024]

[0025] Table 2 Basic characteristics of pipeline concentrate

[0026]

[0027] Table 3 Composition and physicochemical properties of different types of bentonite and binders

[0028]

[0029] Table 4 Ratio of each binder to pipeline concentrate and green ball drop strength

[0030] name Ratio, % Drop strength, times / piece Guyang Bentonite 3 5.45 Belt bentonite 3 5.0 Composite binder (QNP-8) 2.6 5.35

[0031] Table 5 Finished ductile iron grade and compressive strength

[0032]

[0033]

[0034] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A comprehensive evaluation method for the quality and performance of bentonite and binder for pelletizing, characterized by: The steps include: (1) Select the bentonite or binder to be evaluated and match it with the concentrate as the standard raw material; (2) The standard raw materials in step (1) are used to make green balls using a laboratory ball making tray, and the moisture content of the ball making process is controlled to 8.0% ± 0.5%; (3) The time for preparing the balls in step (2) is controlled within 21 minutes, wherein the time for preparing the mother balls is 2.8-3.2 minutes, the time for growing the balls is 7-9 minutes, and the time for compacting the balls is 8-12 minutes; (4) Determine the drop strength of the green balls in step (3), requiring it to reach ≥5 times / ball, and record the lowest binder ratio that meets the strength requirement. The lower the ratio, the better the performance. (5) preparing finished balls from the green balls that meet the drop strength in step (4), with a drying temperature of 170-190°C and a time of 28-32 min; a preheating temperature of 850-950°C and a time of 8-12 min; and a roasting temperature of 120-01300°C and a time of 8-12 min; (6) The compressive strength and chemical composition of TFe and SiO2 of the finished balls in step (5) are tested. The higher the compressive strength and the higher the grade, the better the quality and performance of the bentonite and the binder.

2. The method for comprehensive evaluation of quality and performance of bentonite and binder for pelletizing according to claim 1, characterized in that: The concentrate used is of surface area ≥ 1500 cm 2 / g, iron concentrate with a spheroidization index ≥0.

25.

3. The method for comprehensive evaluation of quality and performance of bentonite and binder for pelletizing according to claim 1, characterized in that: The laboratory pelletizing disk φ=1000mm.

4. The method for comprehensive evaluation of quality and performance of bentonite and binder for pelletizing according to claim 1, characterized in that: The preparation time of the mother ball is 3 minutes, the growth time of the green ball is 8 minutes, and the compaction time of the green ball is 10 minutes.

5. The method for comprehensive evaluation of quality and performance of bentonite and binder for pelletizing according to claim 1, characterized in that: The temperature of the drying section is 180°C and the time is 30 minutes.

6. The method for comprehensive evaluation of quality and performance of bentonite and binder for pelletizing according to claim 1, characterized in that: The preheating temperature is 900℃ and the time is 10 minutes.

7. The method for comprehensive evaluation of quality and performance of bentonite and binder for pelletizing according to claim 1, characterized in that: The calcination temperature is 1240℃ and the time is 10min.

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