A method for producing sintered ore from a sludgy iron ore concentrate

Abstract

This invention discloses a method for producing sinter from mud-type iron concentrate powder, mainly solving the technical problems of poor sintering performance and difficulty in granulation of mud-type iron concentrate powder in the prior art. The technical solution adopted in this invention is a method for producing sinter from mud-type iron concentrate powder, comprising: 1) ore blending, calculating the mass ratio of mud-type iron concentrate powder, rich hematite powder, sintering return ore, flux, and solid fuel according to the technical quality indicators of the sinter; 2) pretreatment of mud-type iron concentrate powder pre-formed material; 3) preparation and pelletizing of mud-type iron concentrate powder pre-formed material; 4) preparation of matrix material, weighing the rich hematite powder, sintering return ore, flux, and solid fuel in the matrix material raw materials according to the mass ratio of the sinter blended material; 5) preparation of sintering comprehensive homogenized material; 6) distributing and sintering the sintering mixture on a sintering trolley. This invention improves the utilization efficiency of mud-type iron concentrate powder, and the produced sinter has excellent metallurgical properties.

Description

Technical Field

[0001] This invention relates to a method for producing sintered ore, and more particularly to a method for producing sintered ore from mud-type iron concentrate powder, belonging to the field of production technology of sintered ore as a raw material for ironmaking. Background Technology

[0002] Globally, high-quality iron ore powder resources are scarce; most are low-grade ores requiring further processing and purification to obtain concentrate powder with relatively high iron content. In addition, a significant portion of iron ore powder is of the mud-forming type, making it difficult to use. Mud-forming iron concentrate often has a smooth surface, strong self-adhesion, and poor particle displacement, making granulation difficult. Due to its tendency to mud-form, strong self-adhesion, and poor particle displacement performance, mud-forming iron concentrate, when used in sintering production, leads to problems such as small proportions, high viscosity, strong water absorption, and the need for stockpiling space and mixing bins. These issues result in difficulties in organizing transportation, feeding, and mixing; decreased permeability of the sintering bed; reduced utilization coefficient, yield, and strength; and increased solid fuel consumption.

[0003] Effluent-type iron concentrates often contain siderite phases, resulting in low hardness and easy sludge formation of siderite. Typical examples of this type of ore include iron concentrates produced in Jiangsu and Anhui provinces of China. Due to their sludge-forming tendency, strong self-adhesion, and poor granulation properties, efflorescent-type iron concentrates have low utilization rates in conventional sintering production, with the amount consumed far lower than the output. Therefore, improving the granulation effect of easily sludge-forming and difficult-to-granulate concentrates is key to increasing their usage in sintering production.

[0004] Chinese patent CN111763822A discloses "a method for producing sinter from ultrafine iron concentrate powder", which mainly solves the problem of improving the sintering performance of ultrafine iron concentrate powder. It precisely adjusts the proportion of various raw materials according to the technical quality indicators of sintered ore and controls key parameters such as MgO, FeO content and alkalinity. In terms of process, a primary mixture is first prepared by mixing a portion of ultrafine iron concentrate powder with other raw materials. Then, a pre-mixed material containing a specific proportion of bentonite is prepared. The two are mixed to form a comprehensive sintering mixture and then sintered.

[0005] Chinese patent CN117887960A discloses "a granulation method for high proportion of specular hematite", which mainly provides a solution for the characteristics of specular hematite.

[0006] Existing technologies for mud-type iron concentrate powder suffer from technical problems such as difficulty in granulation, poor sintering performance, and low utilization rate. Summary of the Invention

[0007] The purpose of this invention is to provide a method for producing sinter from mud-type iron concentrate powder, which mainly solves the technical problems of poor sintering performance and difficulty in granulation of mud-type iron concentrate powder in the prior art.

[0008] The technical route of this invention is as follows: the sintering raw materials are divided into two parts: pre-granulated material and matrix material. The pre-granulated material is prepared by drying and reducing the moisture content of the mud-type iron concentrate, then mixing it with finely ground olivine and bentonite, and finally wetting and pre-granulating it in a disc pelletizer to produce small balls with a diameter of 2.0–4.0 mm. For the matrix material, other iron ore powder, sintering return ore, quicklime, limestone, dolomite chips, and fuel are mixed with water in a certain proportion, granulated, and then a matrix mixture is obtained. After mixing the pre-granulated material and the matrix mixture, the mixture is spread onto a sintering trolley, then ventilated and ignited to finally obtain high-quality sinter.

[0009] The technical solution adopted in this invention is a method for producing sinter from mud-type iron concentrate powder, comprising the following steps:

[0010] 1) Ore blending: Calculate the blending mass ratio of mud-type iron concentrate powder, hematite rich ore powder, sinter return ore, flux and solid fuel based on the technical quality indicators of sinter. Control the mass percentage of MgO in the sinter to be 1.5-2.0%, the mass percentage of FeO to be 8.0-9.5%, and the basicity (CaO / SiO2) of the sinter to be 1.8-2.2.

[0011] 2) Pretreatment of mud-type iron concentrate powder pre-processing: The mud-type iron concentrate powder is dried to control the water content in the mud-type iron concentrate powder to be <3.0% by mass; the olivine ore is finely ground to control the particle size of the olivine ore powder to be ≤60μm.

[0012] 3) Preparation and pelletizing of argillaceous iron concentrate pre-material: Arillaceous iron concentrate powder, olivine ore powder, and bentonite are mixed in a high-performance mixer for 3-5 minutes to obtain argillaceous iron concentrate pre-material. The argillaceous iron concentrate pre-material is then wetted and pelletized in a disc pelletizer to produce argillaceous iron concentrate pre-material pellets with a diameter of 3.0-5.0 mm. The mass percentage of each component in the argillaceous iron concentrate pre-material is as follows: argillaceous iron concentrate powder 97.5%-98.5%, olivine ore powder 0.2%-0.5%, and bentonite 1.0%-2.0%, with the sum of the mass percentages of all components being 100%. The mass percentage of water in the argillaceous iron concentrate pre-material pellets is 6.0%-8.0%.

[0013] 4) Prepare the matrix material. Weigh the hematite rich ore powder, sintered return ore, flux, and solid fuel in the matrix material raw materials according to the mass ratio of the sintered ore. The mass percentage of each component in the matrix material raw materials is as follows: hematite rich ore powder 63.0%–75.0%, sintered return ore 8.0%–15.0%, flux 12.0%–18.0%, and solid fuel 3.0%–5.0%, with the sum of the mass percentages of each component being 100%. Use a primary mixer to mix the hematite rich ore powder, sintered return ore, flux, and solid fuel. Add water during the mixing process. After mixing for 2–4 minutes, the matrix material is prepared, with a water mass percentage of 6.8%–8.0%. The matrix material is then conveyed to a mixing granulator.

[0014] 5) Prepare the sintering composite homogenate. First, granulate the matrix material using a mixing granulator for 2-4 minutes. Then, add the pre-formed mud-type iron concentrate powder into the mixing granulator and mix for 1-2 minutes to prepare the sintering composite homogenate. The mass percentage of each component in the sintering composite homogenate is as follows: pre-formed mud-type iron concentrate powder 2.0%-30.0%, matrix material 70.0%-98.0%.

[0015] 6) The sintering mixture is placed and sintered under exhaust ventilation on the sintering trolley. The thickness of the sintering mixture layer is controlled to be 700-1000 mm. The sintering mixture is ignited and sintered under exhaust ventilation to produce sintered ore. The exhaust negative pressure is controlled to be 13.5-17.0 kPa and the ignition temperature is 1180-1350℃ during the sintering process.

[0016] In this invention, the particle size of the sintered return ore is ≤5.0mm.

[0017] The solid fuel is any one of coke powder, anthracite powder, or a mixture of coke powder and anthracite powder; the mass percentage of carbon in the solid fuel is 77% to 85%; and solid fuel with a particle size ≤ 3.0 mm accounts for more than 90% of the total mass of solid fuel.

[0018] The flux comprises quicklime, limestone powder, and dolomite powder. The mass percentage of each component in the flux is as follows: quicklime 41%–45%, limestone powder 33%–36%, and dolomite powder 22%–24%. Flux particles with a diameter ≤3mm account for more than 90% of the total mass of the flux. The mass percentage of CaO in the quicklime is 80%–90%. The mass percentage of CaO in the limestone powder is 50%–53%. The mass percentage of MgO in the dolomite powder is 19%–22%, and the mass percentage of CaO is 29%–33%.

[0019] Furthermore, in step 3), a disc pelletizer is used to pelletize the mud-type iron concentrate powder pre-processed material. Controlling the rotation speed of the disc pelletizer to 23-27 r / min yields good results.

[0020] In step 3), the compressive strength of the precast spheroidized iron concentrate powder is ≥16N / P.

[0021] The applicant's years of research have revealed that reducing moisture pretreatment enhances the dispersion of mud-type iron concentrate, promoting uniform composition. Since mud-type iron concentrate contains a certain amount of siderite, adding a small amount of olivine powder can enhance granulation. Under the combined effect of these two processes, high-quality pre-granulated green pellets can be obtained. Due to the good strength of the pre-granulated green pellets, they can complete normal sintering after being combined with the matrix material, resulting in high-quality sinter.

[0022] Compared with existing technologies, this invention has the following positive effects: 1. The method of this invention can effectively strengthen the granulation of mud-type iron concentrate, improve the permeability of the sintering bed, and increase production capacity. 2. The binder used in this invention is relatively inexpensive, readily available, and used in small quantities, yet it can effectively achieve a binding effect. 3. The method of this invention is simple in process and requires little investment; it can be implemented with simple modifications to a disc pelletizer and a belt conveyor. 4. The method of this invention uses a small amount of binder, which has little impact on the iron grade of sinter or pellets. Using 1.0% binder, the iron grade of sinter is reduced by only 0.1 percentage points. 5. Based on the characteristic that mud-type iron concentrate contains a certain amount of siderite, the method of this invention adds finely ground olivine, which can increase the strength of pre-formed pellets of mud-type iron concentrate powder and improve the metallurgical properties of sinter. Detailed Implementation

[0023] The present invention will be further illustrated below with reference to specific embodiments.

[0024] Example 1: The solid fuel is coke powder; the C mass percentage in the solid fuel is 77-85%; the solid fuel with a particle size ≤3mm accounts for more than 85% of the total mass of the solid fuel; the mud-type iron concentrate powder is mud-type iron concentrate powder produced in Nanjing City, Jiangsu Province, China.

[0025] A method for producing sinter from mud-type iron concentrate powder includes the following steps:

[0026] 1) Ore blending: Calculate the blending mass ratio of mud-type iron concentrate powder, hematite rich ore powder, sinter return ore, flux and solid fuel based on the technical quality indicators of sinter. Control the mass percentage of MgO in the sinter to be 1.5-2.0%, the mass percentage of FeO to be 8.0-9.5%, and the basicity (CaO / SiO2) of the sinter to be 1.8-2.2.

[0027] 2) Pretreatment of mud-type iron concentrate powder pre-processing: The mud-type iron concentrate powder is dried to control the water content in the mud-type iron concentrate powder to be <3.0% by mass; the olivine ore is finely ground to control the particle size of the olivine ore powder to be ≤60μm.

[0028] 3) Preparation and pelletizing of argillaceous iron concentrate pre-material: Arillaceous iron concentrate powder, olivine ore powder, and bentonite are mixed in a high-performance mixer for 5 minutes to obtain argillaceous iron concentrate pre-material. The argillaceous iron concentrate pre-material is then wetted and pelletized in a disc pelletizer to produce argillaceous iron concentrate pre-material pellets with a diameter of 3.2 mm. The rotation speed of the disc pelletizer is controlled at 25 r / min. The mass percentage of each component in the argillaceous iron concentrate pre-material is: argillaceous iron concentrate powder 98.3%, olivine ore powder 0.5%, and bentonite 1.2%. The mass percentage of water in the argillaceous iron concentrate pre-material pellets is 7.0%.

[0029] 4) Prepare the matrix material. Weigh the hematite rich ore powder, sintered return ore, flux, and solid fuel in the matrix material raw materials according to the mass ratio of the sintered ore. The mass percentage of each component in the matrix material raw materials is as follows: hematite rich ore powder 71.0%, sintered return ore 10.0%, flux 15.0%, and coke powder 4.0%. Use a primary mixer to mix the hematite rich ore powder, sintered return ore, flux, and solid fuel. Add water during the mixing process. After mixing for 4 minutes, the matrix material is prepared. The mass percentage of water in the matrix material is 7.2%. The matrix material is then conveyed to a mixing granulator.

[0030] 5) To prepare the sintering composite homogenate, first granulate the matrix material using a mixing granulator for 4 minutes, then add the pre-formed mud-type iron concentrate powder into the mixing granulator and mix for 2 minutes to prepare the sintering composite homogenate. The mass percentage of each component in the sintering composite homogenate is: 30.0% pre-formed mud-type iron concentrate powder and 70.0% matrix material.

[0031] 6) The sintering mixture is placed and sintered by ventilation on the sintering trolley. The thickness of the sintering mixture layer is controlled to be 750mm. The sintering mixture is ignited and sintered by ventilation to produce sintered ore. The ventilation negative pressure is controlled to be 15.0kPa and the ignition temperature is 1250℃ during the sintering process.

[0032] In the existing process, the proportion of mud-type iron concentrate powder is 5%, which is simultaneously mixed with blended ore, sintering return ore, flux, coke powder and other sintering raw materials and fuels in the batching room according to the batching ratio. After the first and second mixing and granulation, the mixture is made into a mixture and then ignited for sintering to finally obtain sintered ore.

[0033] Table 1. Sinter quality indicators of Example 1 of the present invention

[0034]

[0035] As shown in Table 1, compared with the existing process: In Example 1, the proportion of mud-type iron concentrate powder used increased from 5% to 30%, the yield increased by 0.2 percentage points, and the utilization coefficient improved by 0.04 t / m³. 2•h, solid fuel consumption decreased by 0.70 kg / t, and drum strength increased by 0.6%; although the iron grade decreased by 0.1 percentage points, the benefits brought by the improved utilization rate of mud-type iron concentrate far outweighed the loss of the 0.1 percentage point decrease in iron grade.

[0036] In addition to the embodiments described above, the present invention may have other implementations. All technical solutions formed by equivalent substitution or equivalent transformation fall within the protection scope claimed by the present invention.

Claims

1. A method for producing sinter from mud-type iron concentrate powder, characterized in that, The method includes the following steps: 1) Ore blending: Calculate the blending mass ratio of mud-type iron concentrate powder, hematite rich ore powder, sinter return ore, flux and solid fuel based on the technical quality indicators of sinter. Control the mass percentage of MgO in the sinter to be 1.5-2.0%, the mass percentage of FeO to be 8.0-9.5%, and the basicity (CaO / SiO2) of the sinter to be 1.8-2.

2. 2) Pretreatment of mud-type iron concentrate powder pre-processing: The mud-type iron concentrate powder is dried to control the water content in the mud-type iron concentrate powder to be <3.0% by mass; the olivine ore is finely ground to control the particle size of the olivine ore powder to be ≤60μm. 3) Preparation and pelletizing of argillaceous iron concentrate pre-material: Arillaceous iron concentrate powder, olivine ore powder, and bentonite are mixed in a high-performance mixer for 3-5 minutes to obtain argillaceous iron concentrate pre-material. The argillaceous iron concentrate pre-material is then wetted and pelletized in a disc pelletizer to produce argillaceous iron concentrate pre-material pellets with a diameter of 3.0-5.0 mm. The mass percentage of each component in the argillaceous iron concentrate pre-material is as follows: argillaceous iron concentrate powder 97.5%-98.5%, olivine ore powder 0.2%-0.5%, and bentonite 1.0%-2.0%, with the sum of the mass percentages of all components being 100%. The mass percentage of water in the argillaceous iron concentrate pre-material pellets is 6.0%-8.0%. 4) Prepare the matrix material. Weigh the hematite rich ore powder, sintered return ore, flux, and solid fuel in the matrix material raw materials according to the mass ratio of the sintered ore. The mass percentage of each component in the matrix material raw materials is as follows: hematite rich ore powder 63.0%–75.0%, sintered return ore 8.0%–15.0%, flux 12.0%–18.0%, and solid fuel 3.0%–5.0%, with the sum of the mass percentages of each component being 100%. Use a primary mixer to mix the hematite rich ore powder, sintered return ore, flux, and solid fuel. Add water during the mixing process. After mixing for 2–4 minutes, the matrix material is prepared, with a water mass percentage of 6.8%–8.0%. The matrix material is then conveyed to a mixing granulator. 5) Prepare the sintering composite homogenate. First, granulate the matrix material using a mixing granulator for 2-4 minutes. Then, add the pre-formed mud-type iron concentrate powder into the mixing granulator and mix for 1-2 minutes to prepare the sintering composite homogenate. The mass percentage of each component in the sintering composite homogenate is as follows: pre-formed mud-type iron concentrate powder 2.0%-30.0%, matrix material 70.0%-98.0%. 6) The sintering mixture is placed and sintered under exhaust ventilation on the sintering trolley. The thickness of the sintering mixture layer is controlled to be 700-1000 mm. The sintering mixture is ignited and sintered under exhaust ventilation to produce sintered ore. The exhaust negative pressure is controlled to be 13.5-17.0 kPa and the ignition temperature is 1180-1350℃ during the sintering process.

2. The method for producing sinter from mud-type iron concentrate powder as described in claim 1, characterized in that, A disc pelletizer is used to pelletize the pre-formed mud-type iron concentrate powder, and the rotation speed of the disc pelletizer is controlled at 23-27 r / min.

3. The method for producing sinter from mud-type iron concentrate powder as described in claim 1, characterized in that, The compressive strength of the precast pellets of the mud-type iron concentrate powder is ≥16N / P.

4. The method for producing sinter from mud-type iron concentrate powder as described in claim 1, characterized in that, The particle size of the sintered return ore is ≤5.0mm.

5. The method for producing sinter from mud-type iron concentrate powder as described in claim 1, characterized in that, The solid fuel is any one of coke powder, anthracite powder, or a mixture of coke powder and anthracite powder; the mass percentage of C in the solid fuel is 77% to 85%; Solid fuels with a particle size ≤3.0mm account for more than 90% of the total mass of solid fuels.

6. The method for producing sinter from mud-type iron concentrate powder as described in claim 1, characterized in that, The flux comprises quicklime, limestone powder, and dolomite powder. The mass percentage of each component in the flux is as follows: quicklime 41%–45%, limestone powder 33%–36%, and dolomite powder 22%–24%. Flux particles with a diameter ≤3mm account for more than 90% of the total mass of the flux. The mass percentage of CaO in the quicklime is 80%–90%. The mass percentage of CaO in the limestone powder is 50%–53%. The mass percentage of MgO in the dolomite powder is 19%–22%, and the mass percentage of CaO is 29%–33%.

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