Method for recovering non-uniformly embedded high-silicon specularite and hematite
By combining gravity separation, roasting, magnetic separation, and reverse flotation, the problem of low recovery rate of unevenly disseminated high-silica specular hematite and hematite has been solved, achieving efficient iron recovery and low-cost iron concentrate production. It is highly adaptable and suitable for ores with complex disseminated particle sizes.
Patent Information
- Application Number
- CN202511351292.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-22
- Publication Date
- 2025-11-11
AI Technical Summary
The unevenly distributed high-silica specular hematite and hematite have problems such as low iron recovery rate and substandard concentrate quality during the recovery process. In particular, the complex intergrowth relationship between iron minerals and silica-bearing gangue minerals leads to losses in the tailings during gravity separation. During magnetic separation, silica-bearing gangue and pyrite enter the concentrate, and direct roasting is costly and economically inefficient.
A combined gravity separation-roasting-magnetic separation-reverse flotation process is adopted. Four types of ore are separated by dry vibrating screen. Large particles are processed separately by grinding, coarse/medium particles are separated by shaking table, fine particles are directly roasted, middlings are combined and then reduced roasted and magnetically separated, and finally reverse flotation is used for desiliconization. The process parameters are optimized to improve iron recovery rate and reduce cost.
It achieves efficient recovery of iron concentrate, with iron recovery rate increased to 87.56%-90.12%, concentrate grade stabilized at 64.21%-68.78%, and silicon content controlled at 6.5%-7.54%. It reduces energy consumption and processing costs, has strong adaptability, and is suitable for ores with complex intergrowth particle sizes.
Smart Images
Figure CN120920184A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of mineral processing technology, and in particular to a method for recovering unevenly distributed high-silica specular hematite and hematite. Background Technology
[0002] Specularite, a variant of hematite, has a metallic luster, is flaky, and reddish-brown. It is mainly found in sedimentary metamorphic deposits and contact metasomatic hydrothermal iron ore deposits. It has weak magnetic properties and is traditionally considered a difficult-to-process and utilize ore resource. With the rapid development of the national economy, China's demand for iron ore is increasing dramatically, making it increasingly important to strengthen domestic research on iron ore beneficiation and separation. The specularite ore in a certain region of China has complex properties, especially the complex intergrowth relationship between iron minerals and silica-bearing gangue minerals. The uneven grain size of the intergrowth leads to the loss of high-grade, fine-grained specularite and hematite in the tailings during gravity separation, resulting in low iron recovery and low-quality iron concentrate. When using strong magnetic separation, the intergrowth relationship between specularite, hematite, silica-bearing gangue minerals, and pyrite leads to the inclusion of silica-bearing gangue and a small amount of pyrite in the magnetic separation concentrate, resulting in substandard iron concentrate quality. Direct roasting is costly and economically inefficient.
[0003] This invention addresses the technical shortcomings of current methods for recovering unevenly embedded high-silica mirrors and hematite. It provides a method for recovering these materials. Through classification, a combined process of gravity separation, roasting, magnetic separation, and reverse flotation is employed to achieve efficient iron recovery for different particle sizes. This method features a simple process flow, strong adaptability, and low cost. Summary of the Invention
[0004] This invention provides a combined process of gravity separation-roasting-magnetic separation-reverse flotation to solve the problems of uneven embedding and excessive silicon content.
[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for recovering unevenly distributed high-silica specular hematite and hematite includes the following steps: Step 1: Dry vibrating screening: The crushed ore is vibrated and screened using 2mm, 0.5mm, and 0.074mm screens respectively to obtain four particle sizes: large (+2-3mm), coarse (+0.5-2mm), medium (+0.074-0.5mm), and fine (-0.074mm). Step 2, Large Particle Grinding: The large particles obtained from dry screening are ground to a grinding concentration of 45-55%, and the grinding fineness is such that 100% of the particles are less than 2mm. Step 3: Shaking Table Roughing: Combine the ground large particles with the coarse particles and perform roughing on a shaking table for coarse sand. The roughing conditions are: stroke 15-18mm, stroke rate 250-270 times / min, to obtain shaking table rough concentrate 1, middlings 1, and tailings 1. For medium particles, fine sand is roughed on a shaking table. The roughing conditions are: stroke 10-12mm, stroke rate 320-340 times / min, to obtain shaking table rough concentrate 2, middlings 2, and tailings 2. Step 4, Shaking table refining: Combine rough concentrate 1 and middlings 1 and grind them together. The grinding concentration is 45-55%, and the grinding fineness is -0.074mm, accounting for 60-65%. After grinding, combine them with rough concentrate 2 and middlings 2 and perform fine sand shaking table refining. The refining conditions are: stroke 12-14mm, stroke rate 300-320 times / min, to obtain iron concentrate 1, middlings 3, and tailings 3. Step 5, Reduction roasting: After drying the middle ore 3, mix it with the fine particles obtained in Step 1, add 15-20% carbon powder, and reduce roast at 1000-1250℃ for 0.5-1h to obtain flue gas and roasted sand; Step 6: Grinding the roasted sand: Grind the roasted sand to a concentration of 45-55% and a fineness of -0.074mm accounting for 70-75%; Step 7, Magnetic separation: The slurry ground in step 6 is magnetically separated under a magnetic field strength of 1600-1900 Oe to obtain iron concentrate 2 and tailings 4; Step 8, reverse flotation desilication: Combine iron concentrate 1 and iron concentrate 2, and perform reverse flotation desilication to obtain the final iron concentrate and tailings 5; The iron concentrate has an iron grade of 64.21%-68.78%, an iron recovery rate of 87.56%-90.12%, and a silicon content of 6.5%-7.54%.
[0006] Preferably, in step one, the mass percentages of large particles, coarse particles, medium particles, and fine particles are 25-30%, 35-40%, 20-25%, and 10-15% of the original ore, respectively.
[0007] Preferably, in step three, the stroke of the coarse sand shaking table for coarse selection is 16-17 mm, and the number of strokes is 260±5 times / min.
[0008] Preferably, the carbon powder used in the reduction roasting in step five is anthracite powder with a particle size ≤0.5mm.
[0009] Preferably, the magnetic separation in step seven uses a wet permanent magnet drum magnetic separator.
[0010] Preferably, in step eight, the reverse flotation uses the anionic collector dodecylamine at a dosage of 200-300 g / t.
[0011] Compared with the prior art, the present invention has the following advantages: (1) This invention uses dry vibrating screening to accurately separate four particle size grades of ore and implements differentiated treatment accordingly: large particles are ground separately to ensure precise control of concentration (45-55%) and fineness (100% content of -2mm); coarse / medium particles are separated by shaking tables with appropriate parameters (coarse sand shaking table stroke 15-18mm / stroke 250-270 times / min, fine sand shaking table stroke 10-12mm / stroke 320-340 times / min), directly recovering coarse disseminated iron ore and producing primary concentrate; fine particles are exempt from dewatering pretreatment and directly enter roasting, simplifying the process. This design avoids over-grinding caused by mixed grinding of coarse / medium particles and reduces grinding energy consumption by more than 23%.
[0012] (2) In this invention, the middlings 3 obtained from shaking table beneficiation are combined with the primary fine particles and reduced to magnetite under the conditions of 15-20% carbon powder addition and roasting temperature of 1000-1250℃. After grinding (70-75% of the particles are -0.074mm), the magnetite is efficiently recovered by magnetic separation (1600-1900 Oe), which increases the iron recovery rate of fine particles to 90.5%. After the primary concentrate (iron concentrate 1) and the magnetically separated concentrate (iron concentrate 2) are combined, deep desilication is carried out by reverse flotation to solve the problem of excessive silicon content in the single concentrate. Finally, the iron concentrate is obtained. It stabilized and dropped to 6.5-7.54%.
[0013] (3) The present invention eliminates the filtration and drying processes by direct roasting of fine particles, reducing energy consumption by 40%; the recycling of middlings reduces the amount of grinding required, and combined with the optimization of graded grinding, the processing cost per ton of ore is reduced; the process parameters are flexibly designed (such as the stroke / number of strokes having a floating range), which can be adapted to the embedded particle size of 0.01-3mm. For complex ores with a content of 30-45%, the overall iron recovery rate is increased to over 87.56% compared to traditional processes. Attached Figure Description
[0014] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation
[0015] The present invention will be further described in detail below with reference to specific embodiments.
[0016] Example 1 In Subei County, Gansu Province, a certain iron mine is mainly composed of hematite and its subspecies specularite, with a total iron grade of 32.85% and a silicon content of 40.58%. Hematite and specularite account for 91.23% of the total iron. Mineralogical studies show that the ore has uneven particle size distribution, exhibiting a two-stage differentiation. Dry vibrating screen sieving separated the ore into four particle sizes: large (+2-3 mm), coarse (+0.5-2 mm), medium (+0.074-0.5 mm), and fine (-0.074 mm). Large particles are ground to a grinding concentration of 50%, with 100% of the particles having a fineness of less than 2 mm. The ground large particles are combined with the coarse particles and subjected to roughing on a shaking table with a stroke of 16 mm and a stroke rate of 260 mm, yielding one rough concentrate, one middlings, and one tailings. Medium particles are then roughed on a fine sand shaking table with a stroke of 11 mm and a stroke rate of 330 mm, yielding two rough concentrates, two middlings, and two tailings. The rough concentrate and middlings are then combined and ground to a grinding concentration of 50%, with 63% of the particles having a fineness of -0.074 mm. After grinding, the iron concentrate 2 and middlings 2 are combined and subjected to fine sand shaking table cleaning under the following conditions: stroke 13mm, stroke 310mm, yielding iron concentrate 1, middlings 3, and tailings 3. Middlings 3 is dried and then subjected to reduction roasting with fine particles obtained from dry vibrating screening. The reduction carbon content is 20%, the roasting temperature is 1150℃, and the roasting time is 1h, yielding flue gas and roasted sand. The roasted sand is then ground to a grinding concentration of 50% and a grinding fineness of -0.074mm (72.5%), followed by magnetic separation at a magnetic field strength of 1700Oe, yielding iron concentrate 2 and tailings 4. Iron concentrate 1 and iron concentrate 2 are combined and desilication is achieved using dodecylamine reverse flotation (250g / t), yielding an iron concentrate with an iron grade of 65.35%, an iron recovery rate of 88.35%, and a silicon content of 7.3%. Tailings 1-5 are combined as the final tailings.
[0017] Example 2 A certain iron mine in Jiuquan, Gansu Province, has a total iron content of 30.57% and a silicon content of 42.38%. The iron is mainly composed of hematite, with a small amount of specular hematite. Microscopic observation shows that the iron particles in the ore are unevenly distributed. The ore belongs to a typical high-silicon, uneven hematite type. Dry vibrating screen sieving separated it into four particle sizes: large (+2-3mm), coarse (+0.5-2mm), medium (+0.074-0.5mm), and fine (-0.074mm). Large particles are ground to a grinding concentration of 45%, with 100% of the particles having a fineness of less than 2 mm. The ground large particles are combined with the coarse particles and subjected to roughing on a shaking table with a stroke of 15 mm and a stroke rate of 250 mm, yielding one rough concentrate, one middlings, and one tailings. Medium particles are then roughed on a fine sand shaking table with a stroke of 10 mm and a stroke rate of 320 mm, yielding two rough concentrates, two middlings, and two tailings. The two rough concentrates are then combined and ground to a grinding concentration of 45%, with 65% of the particles having a fineness of -0.074 mm. After grinding, the iron concentrate 2 and middlings 2 are combined and subjected to fine sand shaking table cleaning under the following conditions: stroke 12mm, stroke 300mm, yielding iron concentrate 1, middlings 3, and tailings 3. Middlings 3 is dried and then subjected to reduction roasting with fine particles obtained from dry vibrating screening. The reduction carbon content is 15%, the roasting temperature is 1000℃, and the roasting time is 0.5h, yielding flue gas and roasted sand. The roasted sand is then ground to a grinding concentration of 45% and a grinding fineness of -0.074mm (70%), and subjected to magnetic separation at a magnetic field strength of 1600Oe, yielding iron concentrate 2 and tailings 4. Iron concentrate 1 and iron concentrate 2 are combined and desilication is achieved using dodecylamine reverse flotation (250g / t), yielding an iron concentrate with an iron grade of 64.21%, an iron recovery rate of 87.56%, and a silicon content of 6.5%. Tailings 1-5 are combined as the final tailings.
[0018] Example 3 A certain iron mine in Liaoning Province has a total iron content of 34.48% and a silicon content of 45.37%. The iron is mainly composed of hematite, specular hematite, and limonite, and the iron particles in the ore are unevenly distributed. Dry vibrating screens were used to separate the ore into four particle sizes: large (+2-3 mm), coarse (+0.5-2 mm), medium (+0.074-0.5 mm), and fine (-0.074 mm). Large particles are ground to a grinding concentration of 55%, with 100% of the particles having a fineness of less than 2 mm. The ground large particles are combined with the coarse particles and subjected to roughing on a shaking table with a stroke of 18 mm and a stroke rate of 270 mm, yielding one rough concentrate, one middlings, and one tailings. Medium particles are then roughed on a fine sand shaking table with a stroke of 12 mm and a stroke rate of 340 mm, yielding two rough concentrates, two middlings, and two tailings. The two rough concentrates are then combined and ground to a grinding concentration of 55%, with 60% of the particles having a fineness of -0.074 mm. After grinding, the iron concentrate 2 and middlings 2 are combined and subjected to fine sand shaking table cleaning under the following conditions: stroke 14mm, stroke 320mm, yielding iron concentrate 1, middlings 3, and tailings 3. Middlings 3 is dried and then subjected to reduction roasting with fine particles obtained from dry vibrating screening. The reduction carbon content is 17%, the roasting temperature is 1250℃, and the roasting time is 0.75h, yielding flue gas and roasted sand. The roasted sand is then ground to a grinding concentration of 50% and a grinding fineness of -0.074mm (75%), followed by magnetic separation at a magnetic field strength of 1900Oe, yielding iron concentrate 2 and tailings 4. Iron concentrate 1 and iron concentrate 2 are combined and desilication is achieved using dodecylamine reverse flotation (250g / t), yielding an iron concentrate with an iron grade of 68.78%, an iron recovery rate of 90.12%, and a silicon content of 7.54%. Tailings 1-5 are combined as the final tailings.
[0019] The product yield and analysis results are shown in Table 1.
[0020] Table 1 Product Yield and Analysis Results serial number Iron grade (%) Iron recovery rate (%) Silicon content (%) Example 1 65.35 88.35 7.3 Example 2 64.21 87.56 6.5 Example 3 68.78 90.12 7.54 The data in Table 1 demonstrates that, based on the process data from Examples 1-3, this method exhibits significant stability and adaptability in terms of iron grade improvement, recovery rate optimization, and silicon content control. Within the process parameters defined in the claims, the final iron concentrate grade in all examples consistently reached above 64% (maximum 68.78%), the iron recovery rate consistently exceeded 87.5% (peak 90.12%), and the silica content was strictly controlled below 10% (minimum 6.5%). In particular, when using intermediate parameters (Example 1), the optimal balance between iron grade and desilication effect was achieved (TFe 65.35% / The silicon content was 7.3%, while under extreme parameters (Example 3), although the silicon content increased slightly to 7.54%, the recovery rate exceeded 90% by increasing the magnetic separation field strength (1900 Oe). Therefore, this method effectively achieved high-quality iron concentrate production (≥64%) and high resource recovery rate (≥87.5%), and the silicon impurity removal rate was stable at over 80%.
Claims
1. A method for recovering unevenly distributed high-silica specular hematite and hematite, characterized in that, Includes the following steps: Step 1: Dry vibrating screening: The crushed ore is vibrated and screened using 2mm, 0.5mm, and 0.074mm screens respectively to obtain four particle sizes: large (+2-3mm), coarse (+0.5-2mm), medium (+0.074-0.5mm), and fine (-0.074mm). Step 2, Large Particle Grinding: The large particles obtained from dry screening are ground to a grinding concentration of 45-55%, and the grinding fineness is such that 100% of the particles are less than 2mm. Step 3: Shaking Table Roughing: Combine the ground large particles with the coarse particles and perform roughing on a shaking table for coarse sand. The roughing conditions are: stroke 15-18mm, stroke rate 250-270 times / min, to obtain shaking table rough concentrate 1, middlings 1, and tailings 1. For medium particles, fine sand is roughed on a shaking table. The roughing conditions are: stroke 10-12mm, stroke rate 320-340 times / min, to obtain shaking table rough concentrate 2, middlings 2, and tailings 2. Step 4, Shaking table refining: Combine rough concentrate 1 and middlings 1 and grind them together. The grinding concentration is 45-55%, and the grinding fineness is -0.074mm, accounting for 60-65%. After grinding, combine them with rough concentrate 2 and middlings 2 and perform fine sand shaking table refining. The refining conditions are: stroke 12-14mm, stroke rate 300-320 times / min, to obtain iron concentrate 1, middlings 3, and tailings 3. Step 5, Reduction roasting: After drying the middle ore 3, mix it with the fine particles obtained in Step 1, add 15-20% carbon powder, and reduce roast at 1000-1250℃ for 0.5-1h to obtain flue gas and roasted sand; Step 6: Grinding the roasted sand: Grind the roasted sand to a concentration of 45-55% and a fineness of -0.074mm accounting for 70-75%; Step 7, Magnetic separation: The slurry ground in step 6 is magnetically separated under a magnetic field strength of 1600-1900 Oe to obtain iron concentrate 2 and tailings 4; Step 8, reverse flotation desilication: Combine iron concentrate 1 and iron concentrate 2, and perform reverse flotation desilication to obtain the final iron concentrate and tailings 5; The iron concentrate has an iron grade of 64.21%-68.78%, an iron recovery rate of 87.56%-90.12%, and a silicon content of 6.5%-7.54%.
2. The method for recovering unevenly disseminated high-silica specular hematite and hematite according to claim 1, characterized in that, The mass percentages of large, coarse, medium, and fine particles mentioned in step one are 25-30%, 35-40%, 20-25%, and 10-15% of the original ore, respectively.
3. The method for recovering unevenly disseminated high-silica specular hematite and hematite according to claim 2, characterized in that, In step three, the stroke of the coarse sand shaking table for rough selection is 16-17 mm, and the number of strokes is 260±5 times / min.
4. The method for recovering unevenly disseminated high-silica specular hematite and hematite according to claim 3, characterized in that, The carbon powder used in the reduction roasting in step five is anthracite powder with a particle size ≤0.5mm.
5. The method for recovering unevenly disseminated high-silica specular hematite and hematite according to claim 4, characterized in that, In step seven, a wet permanent magnet drum magnetic separator is used for magnetic separation.
6. The method for recovering unevenly disseminated high-silica specular hematite and hematite according to claim 5, characterized in that, In step (8), the reverse flotation uses dodecylamine, an anionic collector, at a dosage of 200-300 g / t.