Processing method for improving boulder yield of limestone for metallurgical flux

Abstract

The invention belongs to the technical field of limestone processing, and particularly relates to a processing method for improving the boulder rate of limestone for metallurgical flux, which comprises the following steps: pre-screening to remove soil, first-stage crushing, first-stage screening, second-stage crushing, second-stage screening, shaping, third-stage screening and powder selecting. According to the method, the boulder rate of limestone processing for smelting flux can be increased, the fine ore amount is reduced, resource consumption is reduced, the method is more efficient and energy-saving, water resources are not consumed in the whole process, no sewage is generated, all materials except spoil generated by pre-screening soil removal are fully utilized through screening and crushing, and no waste is discharged.

Description

Technical Field

[0001] This invention belongs to the field of limestone processing technology, and in particular relates to a processing method for increasing the proportion of large pieces of limestone used as metallurgical flux. Background Technology

[0002] In the smelting of pig iron, steel, and non-ferrous metals, limestone used as a flux is called flux limestone (also known as metallurgical limestone), and its main chemical component, CaO, is required to have an industrial content of over 50%. Flux limestone can convert impurities in ore and fuel ash into slag, and it also has dephosphorization and desulfurization capabilities, making it a key auxiliary material in the metallurgical process.

[0003] Limestone products for metallurgical flux are typically divided into lump ore (20-40mm, 40-80mm) and fine ore (0-3mm). Market research shows that the demand for lump ore is more than five times that of fine ore. However, traditional processing techniques (such as "jaw crusher + impact crusher" or "hammer crusher + impact crusher") have significant drawbacks: the lump ore yield is only 10-30%, leading to a large accumulation of fine ore; processing 1 ton of qualified lump ore flux requires 3.5-10 tons of raw ore, resulting in high resource consumption; mining and transportation costs are high, and the disposal of fine ore is difficult, easily causing resource waste and environmental pressure.

[0004] Therefore, developing a processing method that can improve the lump ore yield, reduce resource consumption, and is environmentally friendly is of great significance for the efficient and energy-saving production of the metallurgical industry. Summary of the Invention

[0005] The purpose of this invention is to address the above-mentioned problems by providing a processing method for increasing the proportion of large pieces of limestone used in metallurgical fluxes.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a processing method for improving the proportion of large pieces of limestone used in metallurgical fluxes, comprising the following steps: Step 1: After pre-screening and soil removal, the limestone ore enters the primary crushing process, which uses a jaw crusher. The crushed material is then conveyed to a buffer silo. Step Two: The material in the buffer silo is divided into two parts by primary screening. The primary screening uses a bar screen, and the material with a particle size greater than 80mm enters the secondary crushing process. The secondary crushing uses a double toothed roller crusher. The material with a particle size less than 80mm is combined with the discharge from the double toothed roller crusher and then enters the secondary screening process. Step 3: The secondary screening uses a three-layer circular vibrating screen. The upper screen size is 84mm, the middle screen size is 44mm, and the lower screen size is 22mm. After screening, the material with a particle size greater than 80mm is returned to the double-toothed roller crusher for re-crushing. The material with a particle size of 40-80mm and 20-40mm is a lump ore flux product, and the material with a particle size less than 20mm enters the shaping process. Step Four: The shaping process uses a vertical shaft impact crusher to adjust the particle shape of materials with a particle size of 0-20mm before conveying them to the three-stage screening process. Step 5: The three-stage screening uses a double-layer circular vibrating screen. The upper screen size of the double-layer circular vibrating screen is 12mm and the lower screen size is 5mm. After screening, the materials with particle sizes of 10-20mm and 5-10mm are aggregate products, and the materials with particle sizes less than 5mm enter the powder selection process. Step Six: The powder classification process uses a powder classifier to control the grading particle size and powder content, which can produce powdered mineral flux products with a particle size of 0-3mm or manufactured sand products with a particle size of 0-5mm. The dust from the entire production line and the powder separated in the manufactured sand production are all included in the powdered mineral flux products with a particle size of 0-3mm, achieving zero external waste discharge.

[0007] In the above-mentioned processing method for increasing the proportion of large pieces of limestone for metallurgical flux, in step one, the pre-screening and soil removal adopts a double-layer circular vibrating screen with a screen aperture of 10mm, which is used to remove soil and fine powder with a particle size of less than 10mm from the raw ore.

[0008] In the above-mentioned processing method for improving the large-block rate of limestone for metallurgical flux, in step one, the discharge port size of the jaw crusher is adjusted to 80-125mm, the maximum particle size of the crushed material is controlled within 150mm, and the proportion of 80-150mm in the particle size distribution of the crushed product is 60%-70%.

[0009] In the above-mentioned processing method for increasing the proportion of large limestone blocks in metallurgical flux, in step two, the bar screen used for primary screening has a screen gap width of 80mm, a screen bar spacing error of no more than ±2mm, and a screening efficiency of no less than 85%, wherein the screening accuracy of materials with a particle size greater than 80mm is ≥90%.

[0010] In the above-mentioned processing method for improving the proportion of large pieces of limestone for metallurgical flux, in step two, the roller gap of the double-toothed roller crusher is adjusted to 60-75mm, the toothed roller speed is 15-25r / min, the proportion of particles larger than 80mm in the crushed material is ≤5%, and the over-crushing rate (particle size less than 20mm) is ≤15%.

[0011] In the above-mentioned processing method for improving the proportion of large-sized limestone for metallurgical flux, in step three, the actual screening particle size of the upper screen of the three-layer circular vibrating screen is greater than 84mm (corresponding to materials greater than 80mm), the actual screening particle size of the middle screen is 44-84mm (corresponding to materials 40-80mm), and the actual screening particle size of the lower screen is 22-44mm (corresponding to materials 20-40mm). The screening rate of the upper screen for materials with a particle size greater than 80mm is ≥92%, the screening accuracy of the middle screen for materials with a particle size of 40-80mm is ≥90%, and the screening accuracy of the lower screen for materials with a particle size of 20-40mm is ≥90%.

[0012] In the above-mentioned processing method for increasing the proportion of large limestone blocks for metallurgical flux, in step four, the rotor speed of the vertical shaft impact crusher is 1200-1600 r / min, the gap between the crushing chamber and the rotor is 5-12 mm, and after adjusting the particle shape of 0-20 mm materials, the proportion of needle-shaped and flaky particles is reduced to ≤12%, and the proportion of materials with a particle size of less than 5 mm is ≤30%.

[0013] In the above-mentioned processing method for increasing the proportion of large pieces of limestone for metallurgical flux, in step five, the actual screening particle size of the upper screen of the double-layer circular vibrating screen is 12-22mm (corresponding to material size of 10-20mm), and the actual screening particle size of the lower screen is 5-12mm (corresponding to material size of 5-10mm).

[0014] In the above-mentioned processing method for increasing the proportion of large limestone blocks in metallurgical flux, in step six, the air classifier adopts an air-classifying equipment. The air speed is controlled by adjusting the fan frequency. When producing 0-3mm powder flux products, the air speed is controlled at 12-16m / s to ensure that the proportion of particles smaller than 3mm in the product is ≥95%. When producing 0-5mm manufactured sand products, the air speed is controlled at 8-11m / s to ensure that the proportion of particles smaller than 5mm in the product is ≥95%.

[0015] Compared with existing technologies, the advantages of this invention are as follows: 1. Significantly improved lump ore rate: Through the combined crushing method of "jaw crusher + double toothed roller crusher" and multi-stage precision screening, the lump ore (20-40mm, 40-80mm) rate can reach 50-70%, which is much higher than the 10-30% of the traditional process, greatly reducing the problem of powder ore accumulation.

[0016] 2. Reduced resource consumption: With the increase in lump ore rate, the raw ore consumption for processing 1 ton of qualified lump ore flux is reduced to 1.5 to 2 tons, which saves more than 60% energy compared with the traditional process (3.5 to 10 tons).

[0017] 3. Excellent environmental performance: The entire process does not consume water resources and generates no wastewater. Except for the waste soil generated from pre-screening and soil removal, all materials are fully utilized through screening and crushing, with no external waste discharge, meeting the requirements of green production.

[0018] 4. Product diversification: In addition to lump ore flux, it can also produce aggregates and fine ore / manufactured sand products, thereby improving the comprehensive utilization rate of resources. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating a processing method for improving the bulk yield of limestone used in metallurgical fluxes, provided by the present invention. Figure 2 This is a schematic diagram of the operation steps of a processing method for improving the large-block yield of limestone for metallurgical flux provided by the present invention. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0021] like Figures 1-2 As shown, a processing method for increasing the proportion of large pieces of limestone used in metallurgical flux includes the following steps: Step 1: After pre-screening and soil removal, the limestone ore enters the primary crushing process. The pre-screening and soil removal uses a double-layer circular vibrating screen with a screen aperture of 10mm to remove soil and fine powder with a particle size of less than 10mm from the ore. The primary crushing is carried out by a jaw crusher. The crushed material is conveyed to a buffer bin. The discharge port size of the jaw crusher is adjusted to 80-125mm. The maximum particle size of the crushed material is controlled within 150mm. The proportion of 80-150mm particles in the particle size distribution of the crushed product is 60%-70%. Step Two: The material in the buffer silo is divided into two parts by primary screening. Primary screening uses a bar screen, where material with a particle size greater than 80mm enters the secondary crushing process. The bar screen used in primary screening has a screen gap width of 80mm, a bar spacing error of no more than ±2mm, and a screening efficiency of no less than 85%. The screening accuracy of material with a particle size greater than 80mm is ≥90%. Secondary crushing uses a double toothed roller crusher. Material with a particle size less than 80mm is combined with the discharge from the double toothed roller crusher and enters the secondary screening process. The roller gap of the double toothed roller crusher is adjusted to 60-75mm, and the toothed roller speed is 15-25r / min. The proportion of material with a particle size greater than 80mm in the crushed material is ≤5%, and the over-crushing rate (particle size less than 20mm) is ≤15%. Step 3: The secondary screening uses a three-layer circular vibrating screen. The upper screen size is 84mm, the middle screen size is 44mm, and the lower screen size is 22mm. The actual particle size screened by the upper screen is greater than 84mm (corresponding to material larger than 80mm), the middle screen size is 44-84mm (corresponding to material 40-80mm), and the lower screen size is 22-44mm (corresponding to material 20-40mm). The upper screen has a screening rate of ≥92% for materials with a particle size greater than 80mm, the middle screen has a screening accuracy of ≥90% for materials with a particle size of 40-80mm, and the lower screen has a screening accuracy of ≥90% for materials with a particle size of 20-40mm. After screening, materials with a particle size greater than 80mm are returned to the double-toothed roller crusher for re-crushing, materials with a particle size of 40-80mm and 20-40mm are used as lump ore flux products, and materials with a particle size less than 20mm are used in the shaping process. Step Four: The shaping process uses a vertical shaft impact crusher to adjust the particle shape of materials with a particle size of 0-20mm before conveying them to the three-stage screening process. The rotor speed of the vertical shaft impact crusher is 1200-1600 r / min, and the gap between the crushing chamber and the rotor is 5-12mm. After adjusting the particle shape of materials with a particle size of 0-20mm, the proportion of needle-shaped and flaky particles is reduced to ≤12%, and the proportion of materials with a particle size of less than 5mm is ≤30%. Step 5: The three-stage screening uses a double-layer circular vibrating screen. The upper screen size is 12mm and the lower screen size is 5mm. After screening, materials with particle sizes of 10-20mm and 5-10mm are aggregate products, while materials with particle sizes less than 5mm enter the powder selection process. The actual screening particle size of the upper screen of the double-layer circular vibrating screen is 12-22mm (corresponding to material size of 10-20mm), and the actual screening particle size of the lower screen is 5-12mm (corresponding to material size of 5-10mm). Step Six: The powder classification process uses a classifier to control the grading particle size and powder content, which can produce powdered mineral flux products with a particle size of 0-3mm or manufactured sand products with a particle size of 0-5mm. The dust from the entire production line and the powder separated during the production of manufactured sand are all included in the powdered mineral flux products with a particle size of 0-3mm, achieving zero external waste discharge. The classifier adopts an air-classification equipment, and the wind speed is controlled by adjusting the fan frequency. When producing 0-3mm powdered mineral flux products, the wind speed is controlled at 12-16m / s to ensure that the proportion of particles with a particle size of less than 3mm in the product is ≥95%. When producing 0-5mm manufactured sand products, the wind speed is controlled at 8-11m / s to ensure that the proportion of particles with a particle size of less than 5mm in the product is ≥95%.

[0022] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A processing method for increasing the proportion of large pieces of limestone used in metallurgical fluxes, characterized in that, Includes the following steps: Step 1: After pre-screening and soil removal, the limestone ore enters the primary crushing process, which uses a jaw crusher. The crushed material is then conveyed to a buffer silo. Step Two: The material in the buffer silo is divided into two parts by primary screening. The primary screening uses a bar screen, and the material with a particle size greater than 80mm enters the secondary crushing process. The secondary crushing uses a double toothed roller crusher. The material with a particle size less than 80mm is combined with the discharge from the double toothed roller crusher and then enters the secondary screening process. Step 3: The secondary screening uses a three-layer circular vibrating screen. The upper screen size is 84mm, the middle screen size is 44mm, and the lower screen size is 22mm. After screening, the material with a particle size greater than 80mm is returned to the double-toothed roller crusher for re-crushing. The material with a particle size of 40-80mm and 20-40mm is a lump ore flux product, and the material with a particle size less than 20mm enters the shaping process. Step Four: The shaping process uses a vertical shaft impact crusher to adjust the particle shape of materials with a particle size of 0-20mm before conveying them to the three-stage screening process. Step 5: The three-stage screening uses a double-layer circular vibrating screen. The upper screen size of the double-layer circular vibrating screen is 12mm and the lower screen size is 5mm. After screening, the materials with particle sizes of 10-20mm and 5-10mm are aggregate products, and the materials with particle sizes less than 5mm enter the powder selection process. Step Six: The powder classification process uses a powder classifier to control the grading particle size and powder content, which can produce powdered mineral flux products with a particle size of 0-3mm or manufactured sand products with a particle size of 0-5mm. The dust from the entire production line and the powder separated in the manufactured sand production are all included in the powdered mineral flux products with a particle size of 0-3mm, achieving zero external waste discharge.

2. The processing method for increasing the proportion of large pieces of limestone for metallurgical flux according to claim 1, characterized in that, In step one, the pre-screening and soil removal adopts a double-layer circular vibrating screen with a screen aperture of 10mm, which is used to remove soil and fine powder with a particle size of less than 10mm from the raw ore.

3. The processing method for increasing the proportion of large pieces of limestone for metallurgical flux according to claim 1, characterized in that, In step one, the discharge port size of the jaw crusher is adjusted to 80-125mm, the maximum particle size of the crushed material is controlled within 150mm, and the proportion of 80-150mm in the particle size distribution of the crushed product is 60%-70%.

4. The processing method for increasing the proportion of large pieces of limestone for metallurgical flux according to claim 1, characterized in that, In step two, the bar screen used for primary screening has a screen gap width of 80mm, a screen bar spacing error of no more than ±2mm, and a screening efficiency of no less than 85%, wherein the screening accuracy of materials with a particle size greater than 80mm is ≥90%.

5. The processing method for increasing the proportion of large pieces of limestone for metallurgical flux according to claim 1, characterized in that, In step two, the roller gap of the double toothed roller crusher is adjusted to 60-75mm, the toothed roller speed is 15-25r / min, the proportion of particles larger than 80mm in the crushed material is ≤5%, and the over-crushing rate (particle size less than 20mm) is ≤15%.

6. The processing method for increasing the proportion of large pieces of limestone for metallurgical flux according to claim 1, characterized in that, In step three, the actual particle size sieved by the upper screen of the three-layer circular vibrating screen is greater than 84mm (corresponding to material larger than 80mm), the actual particle size sieved by the middle screen is 44-84mm (corresponding to material 40-80mm), and the actual particle size sieved by the lower screen is 22-44mm (corresponding to material 20-40mm). The screening rate of the upper screen for materials with a particle size greater than 80mm is ≥92%, the screening accuracy of the middle screen for materials with a particle size of 40-80mm is ≥90%, and the screening accuracy of the lower screen for materials with a particle size of 20-40mm is ≥90%.

7. The processing method for increasing the proportion of large pieces of limestone for metallurgical flux according to claim 1, characterized in that, In step four, the rotor speed of the vertical shaft impact crusher is 1200-1600 r / min, the gap between the crushing chamber and the rotor is 5-12 mm, and after adjusting the particle shape of the 0-20 mm material, the proportion of needle-shaped particles is reduced to ≤12%, and the proportion of material with a particle size of less than 5 mm is ≤30%.

8. The processing method for increasing the proportion of large pieces of limestone for metallurgical flux according to claim 1, characterized in that, In step five, the actual particle size of the upper screen of the double-layer circular vibrating screen is 12-22mm (corresponding to 10-20mm material), and the actual particle size of the lower screen is 5-12mm (corresponding to 5-10mm material).

9. A processing method for increasing the proportion of large pieces of limestone for metallurgical flux according to claim 1, characterized in that, In step six, the air classifier is an air classifier. The air speed is controlled by adjusting the fan frequency. When producing 0-3mm powder flux products, the air speed is controlled at 12-16m / s to ensure that the proportion of particles with a diameter less than 3mm in the product is ≥95%. When producing 0-5mm manufactured sand products, the air speed is controlled at 8-11m / s to ensure that the proportion of particles with a diameter less than 5mm in the product is ≥95%.

Images