Method for selective dissociation of iron minerals in iron tailings and jet capture

Abstract

The application discloses a method for selective dissociation of iron minerals in iron tailings and jet flow capturing, and belongs to the field of micro-fine particle mineral flotation recovery and tailings resource recovery, and steps are as follows: an Aixi sand mill is used for grinding, and parameters such as medium size, stirring shaft rotating speed, medium filling rate, pulp concentration and material ball ratio are adjusted to control the particle size of the grinding product; the jet flow flotation test device is used for flotation of the grinding product, and parameters such as pulp concentration, circulating amount, air filling amount and reagent system are adjusted to control the flotation index. The Aixi sand mill is used for grinding of the iron tailings, and the selective grinding technology of 'large grinding large and small grinding small' is used to improve the single dissociation effect of the micro-fine particle iron minerals and gangue minerals in the tailings; and then the jet flow flotation method is used to strengthen the flotation recovery of the micro-fine particle iron minerals. The above method realizes the integrated treatment of fine grinding and effective separation of the ore, and realizes the secondary development and utilization of the iron tailings, and effectively improves the self-sufficiency rate of the iron ore resources in China.

Description

Technical Field

[0001] This invention belongs to the field of flotation recovery of fine-grained minerals and resource recovery of tailings, specifically involving a method for selective dissociation and jet capture of iron minerals in iron tailings. Background Technology

[0002] The typical characteristics of my country's iron ore resources are a scarcity of high-grade ore, an abundance of low-grade ore, and a prevalence of multi-component associated ores. With the continuous development of mineral resources and limitations imposed by early beneficiation technologies and equipment, a large amount of valuable resources remain in the tailings. Meanwhile, the average grade of iron ore entering the beneficiation process in my country is less than 30%, and more than 2 tons of tailings are generated for every ton of iron concentrate produced. Therefore, research on resource recovery from iron tailings has attracted significant attention. Currently, the annual output of tailings in China remains above 1 billion tons, of which about 40% is iron ore tailings. The large-scale stockpiling of these iron tailings has had a detrimental impact on the environment, safety, and economy. Therefore, strengthening the resource recovery and utilization of iron tailings can not only reduce waste emissions but also mitigate environmental impacts and achieve sustainable resource utilization.

[0003] Starch, as a natural polysaccharide polymer, has wide applications in iron ore flotation. However, with the increasing fineness of the mineral feed particles and the complexity of their intergrowth relationships, the traditional properties of starch, such as stability, solubility, and dispersibility, are no longer effective in iron ore reverse flotation to achieve satisfactory results. Therefore, improving starch performance through modification is currently a research hotspot. The main modification method is chemical modification, but this process easily generates numerous byproducts that negatively impact its performance.

[0004] Ordinary iron tailings have complex mineral and chemical compositions, and are characterized by low content of easily beneficiated iron minerals such as magnetite and hematite, as well as uneven particle size distribution of iron minerals. Although complex and difficult-to-beneficiate tailings have high iron content, they all require targeted treatment to effectively recover valuable components. For Anshan-type iron tailings, the main problems are the enrichment of iron in fine-grained particles and the large amount of mud-like minerals present. The key issues in utilizing these iron tailings are the difficulty in efficiently liberating the target mineral from gangue minerals and the challenges of flotation of fine-grained particles. Therefore, addressing the ore liberation problem and strengthening the flotation of fine-grained minerals are crucial for the utilization of these tailings. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention proposes a method for selective dissociation and jet capture of iron minerals in iron tailings, aiming to improve or solve the difficulties or key problems in the flotation and recycling of fine-grained iron tailings.

[0006] A method for selective dissociation and jet capture of iron minerals in iron tailings specifically includes the following steps:

[0007] Step 1. Feed the high-silicon iron tailings into the mixing tank and adjust the slurry concentration to 30%–60%;

[0008] Step 2. Feed the slurry prepared in Step 1 into an abrasive mill for grinding to obtain the ground product;

[0009] Step 3. The grinding product obtained in Step 2 is transported to a jet flotation machine via a slurry pump for the flotation and recovery of iron minerals;

[0010] Step 4. After adding reagents into the jet flotation machine, the flotation operation is carried out. First, the pH of the pulp is adjusted with a modifier, and then the inhibitor, activator and collector are added in sequence. The froth product on the surface is the tailings, and the concentrate flows out with the underflow of the flotation machine.

[0011] The inhibitor is a modified starch, selected from one or more of modified cassava starch, modified corn starch, or modified wheat starch, and its dosage is 600-1000 g / t; when multiple inhibitors are selected, the multiple inhibitors are in equal mass ratio.

[0012] in:

[0013] In step 1, the TFe grade of the high-silicon iron tailings is 23% to 30%, and the proportion of particles with a size of -38μm is 70% to 95%.

[0014] In step 2, the media size of the sand mill is 3-7mm, the stirring shaft speed is 1000-2500rpm, the media filling rate is 25%-40%, and the unit processing capacity is 20-100L / h.

[0015] In step 3, the operating conditions for flotation recovery are: pulp concentration 30%–50%, circulation rate 20–50 m³ / h. 3 / h, inflation volume 5-10m 3 / h.

[0016] In step 4, the adjusting agent is NaOH, and its dosage is 200-400 g / t, and the pH of the slurry is 9-11.

[0017] In step 4, the preparation process of the modified starch is as follows:

[0018] (1) Under the conditions of a roller speed of 800-1200 rpm and a grinding time of 50-100 min, starch is ground using a roller mill to increase its surface area;

[0019] (2) After grinding starch and acetamide are mixed in a mass ratio of (1-5):1, they are dissolved in epichlorohydrin, wherein the mass ratio of the starch and acetamide mixture to epichlorohydrin is 100:(3-7).

[0020] (3) Mix starch, acetamide and epichlorohydrin evenly and feed them into the plasma reactor, and ensure that they are evenly distributed in the reactor;

[0021] (4) The plasma reactor uses hydrogen pressurized plasma jet to process starch;

[0022] The conditions for treating starch by plasma jet are as follows: plasma reactor pressure is 0.4-1.0 MPa, temperature is controlled at 50-80℃, jet time is 3-10 min, and power is 500-1000 W.

[0023] (5) The starch was washed with ethanol to remove unreacted acetamide and epichlorohydrin, and then dried at low temperature to obtain modified starch.

[0024] In step 4, the activator is CaO, and its dosage is 600-800 g / t.

[0025] In step 4, the collector is one or a combination of TD-2 and DZ-1, and its dosage is 300-800 g / t; when multiple collectors are used, the molar ratio between the multiple collectors is 1:1.

[0026] The concentrate obtained using this method has a TFe grade of ≥60% and a recovery rate of ≥30%.

[0027] Compared with existing technologies, the method provided by this invention has the following advantages:

[0028] (1) In this invention, selective liberation of fine-grained iron tailings and jet flotation enable efficient recovery and utilization. The use of an abrasive mill for fine grinding, employing a selective grinding technique of "large mill for large particles, small mill for small particles," grinds the ore into finer particles and effectively enhances the liberation of fine-grained iron minerals and gangue minerals in the tailings. The efficient liberation of minerals achieved by the abrasive mill during grinding provides a good ore base for subsequent flotation and improves beneficiation efficiency.

[0029] (2) To address the problem of the difficulty in effectively flotating and recovering fine-grained minerals, this invention employs a jet flotation machine for flotation operations. The fine-grained minerals undergo two mineralization processes: pipe mineralization and high-turbulence mineralization. Furthermore, the selective bridging and agglomeration of fine-grained minerals by microbubbles effectively enhances the separation effect. The application of modified starch during the flotation process not only efficiently inhibits the flotation of fine-grained iron ore but also increases the apparent particle size by achieving flocculation of fine-grained minerals through a multi-branched structure.

[0030] (3) Compared with traditional fine particle separation methods, the combination of sand mill and jet flotation can more precisely control the ore processing process and reduce energy consumption. Attached Figure Description

[0031] Figure 1 The diagram shows the equipment connections used in the method for selective dissociation and jet capture of iron minerals in iron tailings in this invention. Detailed Implementation

[0032] Example 1

[0033] A method for selective liberation and jet capture of iron minerals in iron tailings, the equipment connection diagram of which is shown below. Figure 1 As shown, it consists of three parts: a slurry preparation system, a grinding system, and a flotation system, which are connected by a slurry pump and a conveying pipeline. The slurry preparation system is mainly composed of a mixing tank, the main part of the grinding system is an abrasive mill, and the main part of the flotation system is a jet flotation machine.

[0034] The method specifically includes the following steps:

[0035] Step 1. Feed the high-silicon iron tailings with a TFe grade of 24.52% and a particle size of -38μm of 70% into the mixing tank and adjust the slurry concentration to 35%.

[0036] Step 2. Feed the slurry prepared in Step 1 into the abrasive mill and grind it under the conditions of media size of 6 mm, stirring shaft speed of 1000 rpm, media filling rate of 25%, and unit throughput of 40 L / h to obtain the grinding product.

[0037] Step 3. The grinding product obtained in Step 2 is pumped to a jet flotation machine for iron mineral flotation recovery. The operating conditions are: pulp concentration 40% and circulation rate 25m³. 3 / h, inflation volume 5m 3 / h;

[0038] Step 4. After adding reagents into the jet flotation machine, flotation is carried out. First, the pH of the pulp is adjusted to 11 using 200 g / t NaOH. Then, 700 g / t of depressant, 600 g / t of activator, and 400 g / t of collector are added in sequence. The depressant is modified corn starch, the activator is CaO, and the collector is DZ-1. The froth product obtained from flotation is tailings, and the concentrate flowing out with the underflow of the flotation machine is concentrate. Its grade and recovery rate are shown in Table 1.

[0039] The method for preparing modified corn starch is as follows:

[0040] (1) Corn starch was ground using a roller mill at a roller speed of 800 rpm and a grinding time of 60 min to increase its surface area.

[0041] (2) After grinding the corn starch and acetamide in a mass ratio of 3:1, the mixture is dissolved in epichlorohydrin, wherein the mass ratio of the mixture of corn starch and acetamide to epichlorohydrin is 100:7.

[0042] (3) After the corn starch, acetamide and epichlorohydrin are mixed evenly, they are fed into the plasma reactor and ensured that they are evenly distributed in the reactor.

[0043] (4) The plasma reactor uses hydrogen pressurized plasma jet to process corn starch; the plasma reactor pressure is 0.4MPa, the temperature is controlled at 60℃, the jet time is 10min, and the power is 500W.

[0044] (5) The corn starch after washing with ethanol was used to remove unreacted acetamide and epichlorohydrin, and then dried at low temperature to obtain modified corn starch.

[0045] Table 1. Grade and recovery rate of concentrate and tailings obtained in Example 1

[0046] Concentrate 60.28 32.93 Tailings 6.96 67.07 total 24.52 100

[0047] Example 2

[0048] A method for selective dissociation and jet capture of iron minerals in iron tailings specifically includes the following steps:

[0049] Step 1. Feed the high-silicon iron tailings with a TFe grade of 25.97% and a particle size of -38μm of 85% into the mixing tank and adjust the slurry concentration to 50%.

[0050] Step 2. Feed the slurry prepared in Step 1 into the abrasive mill and grind it under the conditions of media size of 4 mm, stirring shaft speed of 2000 rpm, media filling rate of 40%, and unit throughput of 60 L / h to obtain the grinding product.

[0051] Step 3. The grinding product obtained in Step 2 is pumped to a jet flotation machine for iron mineral flotation recovery. The operating conditions are: pulp concentration 30% and circulation rate 40 m³ / h. 3 / h, inflation volume 7m 3 / h;

[0052] Step 4. After adding reagents into the jet flotation machine, flotation is carried out. First, the pH of the pulp is adjusted to 11 using 300 g / t NaOH. Then, 800 g / t of depressant, 650 g / t of activator, and 800 g / t of collector are added in sequence. The depressant is modified wheat starch, the activator is CaO, and the collector is TD-2. The froth product obtained from flotation is tailings, and the concentrate flowing out with the underflow of the flotation machine is concentrate. Its grade and recovery rate are shown in Table 2.

[0053] The method for preparing modified wheat starch is as follows:

[0054] (1) Wheat starch was ground using a roller mill at a roller speed of 800 rpm and a grinding time of 60 min to increase its surface area.

[0055] (2) After grinding wheat starch and acetamide are mixed in a mass ratio of 3:1, they are dissolved in epichlorohydrin, wherein the mass ratio of the mixture of wheat starch and acetamide to epichlorohydrin is 100:7.

[0056] (3) After mixing wheat starch, acetamide and epichlorohydrin evenly, feed them into the plasma reactor and ensure that they are evenly distributed in the reactor;

[0057] (4) The plasma reactor uses hydrogen pressurized plasma jet to process wheat starch; the plasma reactor pressure is 0.4MPa, the temperature is controlled at 60℃, the jet time is 10min, and the power is 500W.

[0058] (5) Wheat starch treated with ethanol is washed to remove unreacted acetamide and epichlorohydrin, and then dried at low temperature to obtain modified wheat starch.

[0059] Table 2. Grade and recovery rate of concentrate and tailings obtained in Example 2

[0060] Concentrate 64.49 31.66 Tailings 8.12 68.34 total 25.97 100

[0061] Example 3

[0062] A method for selective dissociation and jet capture of iron minerals in iron tailings specifically includes the following steps:

[0063] Step 1. Feed the high-silicon iron tailings with a TFe grade of 23.96% and a particle size of -38μm of 80% into the mixing tank and adjust the slurry concentration to 40%.

[0064] Step 2. Feed the slurry prepared in Step 1 into the abrasive mill and grind it under the conditions of media size of 3 mm, stirring shaft speed of 2500 rpm, media filling rate of 25%, and unit throughput of 20 L / h to obtain the grinding product.

[0065] Step 3. The grinding product obtained in Step 2 is pumped to a jet flotation machine for iron mineral flotation recovery. The operating conditions are: pulp concentration 30% and circulation rate 50 m³ / h. 3 / h, inflation volume 7m 3 / h;

[0066] Step 4. After adding reagents into the jet flotation machine, flotation is carried out. First, the pH of the pulp is adjusted to 10.5 with 200 g / t NaOH. Then, 600 g / t of depressant, 800 g / t of activator, and 500 g / t of collector are added in sequence. The depressant is modified corn starch, the activator is CaO, and the collectors are TD-2 and DZ-1 with a molar ratio of 1:1. The froth product obtained from flotation is tailings, and the concentrate flowing out with the underflow of the flotation machine is concentrate. Its grade and recovery rate are shown in Table 3.

[0067] The method for preparing modified corn starch is as follows:

[0068] (1) Corn starch was ground using a roller mill at a roller speed of 800 rpm and a grinding time of 60 min to increase its surface area.

[0069] (2) After grinding the corn starch and acetamide in a mass ratio of 3:1, the mixture is dissolved in epichlorohydrin, wherein the mass ratio of the mixture of corn starch and acetamide to epichlorohydrin is 100:7.

[0070] (3) After the corn starch, acetamide and epichlorohydrin are mixed evenly, they are fed into the plasma reactor and ensured that they are evenly distributed in the reactor.

[0071] (4) The plasma reactor uses hydrogen pressurized plasma jet to process corn starch; the plasma reactor pressure is 0.4MPa, the temperature is controlled at 60℃, the jet time is 10min, and the power is 500W.

[0072] (5) The corn starch after washing with ethanol is used to remove unreacted acetamide and epichlorohydrin. After drying at low temperature, modified corn starch can be obtained.

[0073] Table 3. Grade and recovery rate of concentrate and tailings obtained in Example 3

[0074] Concentrate 62.01 34.1 Tailings 4.28 65.9 total 23.96 100

[0075] Example 4

[0076] A method for selective dissociation and jet capture of iron minerals in iron tailings specifically includes the following steps:

[0077] Step 1. Feed the high-silicon iron tailings with a TFe grade of 26.42% and a particle size of -38μm of 75% into the mixing tank and adjust the slurry concentration to 40%.

[0078] Step 2. Feed the slurry prepared in Step 1 into the abrasive mill and grind it under the conditions of media size of 3 mm, stirring shaft speed of 1400 rpm, media filling rate of 35%, and unit throughput of 30 L / h to obtain the grinding product.

[0079] Step 3. The grinding product obtained in Step 2 is pumped to a jet flotation machine for iron mineral flotation recovery. The operating conditions are: pulp concentration 45% and circulation rate 30 m³ / h. 3 / h, inflation volume 10m 3 / h;

[0080] Step 4. After adding reagents into the jet flotation machine, flotation is carried out. First, the pH of the pulp is adjusted to 10 with 200 g / t NaOH. Then, 750 g / t of depressant, 600 g / t of activator, and 500 g / t of collector are added in sequence. The depressant is modified corn starch, the activator is CaO, and the collector is DZ-1. The froth product obtained from flotation is tailings, and the concentrate flowing out with the underflow of the flotation machine is concentrate. Its grade and recovery rate are shown in Table 4.

[0081] The method for preparing modified corn starch is as follows:

[0082] (1) Corn starch was ground using a roller mill at a roller speed of 1000 rpm and a grinding time of 50 min to increase its surface area.

[0083] (2) After grinding the corn starch and acetamide in a mass ratio of 2:1, the mixture is dissolved in epichlorohydrin, wherein the mass ratio of the mixture of corn starch and acetamide to epichlorohydrin is 100:5.

[0084] (3) After the corn starch, acetamide and epichlorohydrin are mixed evenly, they are fed into the plasma reactor and ensured that they are evenly distributed in the reactor.

[0085] (4) The plasma reactor uses hydrogen pressurized plasma jet to process starch; the plasma reactor pressure is 1MPa, the temperature is controlled at 80℃, the jet time is 5min, and the power is 500W.

[0086] (5) The corn starch after washing with ethanol is used to remove unreacted acetamide and epichlorohydrin. After drying at low temperature, modified corn starch can be obtained.

[0087] Table 4. Grade and recovery rate of concentrate and tailings obtained in Example 4

[0088] Concentrate 62.51 30.17 Tailings 2.12 69.83 total 26.42 100

[0089] Example 5

[0090] A method for selective dissociation and jet capture of iron minerals in iron tailings specifically includes the following steps:

[0091] Step 1. Feed the high-silicon iron tailings with a TFe grade of 26.45% and a particle size of -38μm of 85% into the mixing tank and adjust the slurry concentration to 50%.

[0092] Step 2. Feed the slurry prepared in Step 1 into the abrasive mill and grind it under the conditions of media size of 4 mm, stirring shaft speed of 2000 rpm, media filling rate of 40%, and unit throughput of 50 L / h to obtain the grinding product.

[0093] Step 3. The grinding product obtained in Step 2 is pumped to a jet flotation machine for iron mineral flotation recovery. The operating conditions are: pulp concentration 45% and circulation rate 50 m³ / h. 3 / h, inflation volume 10m 3 / h;

[0094] Step 4. After adding reagents into the jet flotation machine, flotation is carried out. First, the pH of the pulp is adjusted to 11 using 250 g / t NaOH. Then, 600 g / t of depressant, 700 g / t of activator, and 400 g / t of collector are added in sequence. The depressant is modified cassava starch, the activator is CaO, and the collectors are TD-2 and DZ-1 with a molar ratio of 1:1. The froth product obtained from flotation is the tailings, and the concentrate flowing out with the underflow of the flotation machine is the concentrate. Its grade and recovery rate are shown in Table 5.

[0095] The method for preparing modified cassava starch is as follows:

[0096] (1) Cassava starch was ground using a roller mill at a roller speed of 800 rpm and a grinding time of 60 min to increase its surface area.

[0097] (2) After grinding the cassava starch and acetamide in a mass ratio of 3:1, the mixture is dissolved in epichlorohydrin, wherein the mass ratio of the mixture of cassava starch and acetamide to epichlorohydrin is 100:7.

[0098] (3) After mixing the cassava starch, acetamide and epichlorohydrin evenly, feed them into the plasma reactor and ensure that they are evenly distributed in the reactor.

[0099] (4) The plasma reactor uses hydrogen pressurized plasma jet to process cassava starch; the plasma reactor pressure is 0.4 MPa, the temperature is controlled at 60℃, the jet time is 10 min, and the power is 500 W.

[0100] (5) After washing the cassava starch with ethanol, the unreacted acetamide and epichlorohydrin are removed, and the modified cassava starch is obtained after low-temperature drying.

[0101] Table 5. Grade and recovery rate of concentrate and tailings obtained in Example 5.

[0102]

[0103]

[0104] Example 6

[0105] A method for selective dissociation and jet capture of iron minerals in iron tailings specifically includes the following steps:

[0106] Step 1. Feed the high-silicon iron tailings with a TFe grade of 25.19% and a particle size of -38μm of 70% into the mixing tank and adjust the slurry concentration to 40%.

[0107] Step 2. Feed the slurry prepared in Step 1 into the abrasive mill and grind it under the conditions of media size of 5 mm, stirring shaft speed of 1500 rpm, media filling rate of 30%, and unit throughput of 30 L / h to obtain the grinding product.

[0108] Step 3. The grinding product obtained in Step 2 is pumped to a jet flotation machine for iron mineral flotation recovery. The operating conditions are: pulp concentration 50% and circulation rate 20m³. 3 / h, inflation volume 8m 3 / h;

[0109] Step 4. After adding reagents into the jet flotation machine, flotation is carried out. First, the pH of the pulp is adjusted to 11 using 300 g / t NaOH. Then, 800 g / t of depressant, 600 g / t of activator, and 500 g / t of collector are added in sequence. The depressant is modified corn starch and modified wheat starch with a mass ratio of 1:1, the activator is CaO, and the collector is DZ-1. The froth product obtained from flotation is tailings, and the concentrate flowing out with the underflow of the flotation machine is concentrate. Its grade and recovery rate are shown in Table 6.

[0110] The preparation methods for modified corn starch and modified wheat starch are as follows:

[0111] (1) Under the conditions of a roller speed of 800 rpm and a grinding time of 60 min, corn starch and wheat starch were ground separately using a roller mill to increase their surface area.

[0112] (2) The ground corn starch and wheat starch were mixed with acetamide in a mass ratio of 3:1 and then dissolved in epichlorohydrin, wherein the mass ratio of the mixture of corn starch and wheat starch with acetamide to epichlorohydrin was 100:7.

[0113] (3) After the corn starch, wheat starch, acetamide and epichlorohydrin are mixed evenly, they are fed into the plasma reactor and ensured that they are evenly distributed in the reactor.

[0114] (4) The plasma reactor uses hydrogen pressurized plasma jet to process corn starch and wheat starch respectively; the plasma reactor pressure is 0.4MPa, the temperature is controlled at 60℃, the jet time is 10min, and the power is 500W.

[0115] (5) After washing the corn starch and wheat starch with ethanol, the unreacted acetamide and epichlorohydrin are removed, and the modified corn starch and modified wheat starch are obtained after low-temperature drying.

[0116] Table 6. Grade and recovery rate of concentrate and tailings obtained in Example 6

[0117] Concentrate 62.97 30.87 Tailings 8.32 69.13 total 25.19 100

[0118] Example 7

[0119] A method for selective dissociation and jet capture of iron minerals in iron tailings specifically includes the following steps:

[0120] Step 1. Feed the high-silicon iron tailings with a TFe grade of 27.81% and a particle size of -38μm of 80% into the mixing tank and adjust the slurry concentration to 45%.

[0121] Step 2. Feed the slurry prepared in Step 1 into the abrasive mill and grind it under the conditions of media size of 4 mm, stirring shaft speed of 1500 rpm, media filling rate of 35%, and unit throughput of 50 L / h to obtain the grinding product.

[0122] Step 3. The grinding product obtained in Step 2 is pumped to a jet flotation machine for iron mineral flotation recovery. The operating conditions are: pulp concentration 40% and circulation rate 30 m³ / h. 3 / h, inflation volume 7m 3 / h;

[0123] Step 4. After adding reagents into the jet flotation machine, flotation is carried out. First, the pH of the pulp is adjusted to 10.5 with 300 g / t NaOH. Then, 600 g / t of depressant, 700 g / t of activator, and 700 g / t of collector are added in sequence. The depressant is modified cassava starch, the activator is CaO, and the collector is TD-2. The froth product obtained from flotation is tailings, and the concentrate flowing out with the underflow of the flotation machine is concentrate. Its grade and recovery rate are shown in Table 7.

[0124] The method for preparing modified cassava starch is as follows:

[0125] (1) Cassava starch was ground using a roller mill at a roller speed of 1000 rpm and a grinding time of 80 min to increase its surface area.

[0126] (2) After grinding the cassava starch and acetamide in a mass ratio of 4:1, the mixture is dissolved in epichlorohydrin, wherein the mass ratio of the cassava starch and acetamide mixture to epichlorohydrin is 100:5.

[0127] (3) After mixing the cassava starch, acetamide and epichlorohydrin evenly, feed them into the plasma reactor and ensure that they are evenly distributed in the reactor.

[0128] (4) The plasma reactor uses hydrogen pressurized plasma jet to process cassava starch; the plasma reactor pressure is 0.6MPa, the temperature is controlled at 70℃, the jet time is 8min, and the power is 700W.

[0129] (5) After washing the cassava starch with ethanol, the unreacted acetamide and epichlorohydrin are removed, and the modified cassava starch is obtained after low-temperature drying.

[0130] Table 7. Grade and recovery rate of concentrate and tailings obtained in Example 7.

[0131] Concentrate 61.52 32.52 Tailings 11.56 67.48 total 27.81 100

[0132] Example 8

[0133] A method for selective dissociation and jet capture of iron minerals in iron tailings specifically includes the following steps:

[0134] Step 1. Feed the high-silicon iron tailings with a TFe grade of 28.59% and a particle size of -38μm of 90% into the mixing tank and adjust the slurry concentration to 45%.

[0135] Step 2. Feed the slurry prepared in Step 1 into the abrasive mill and grind it under the conditions of media size of 3 mm, stirring shaft speed of 2500 rpm, media filling rate of 40%, and unit throughput of 60 L / h to obtain the grinding product.

[0136] Step 3. The grinding product obtained in Step 2 is pumped to a jet flotation machine for iron mineral flotation recovery. The operating conditions are: pulp concentration 40% and circulation rate 30 m³ / h. 3 / h, inflation volume 8m 3 / h;

[0137] Step 4. After adding reagents into the jet flotation machine, flotation is carried out. First, the pH of the pulp is adjusted to 11 using 400 g / t NaOH. Then, 700 g / t of depressant, 700 g / t of activator, and 800 g / t of collector are added in sequence. The depressant is modified corn starch, the activator is CaO, and the collector is TD-2. The froth product obtained from flotation is tailings, and the concentrate flowing out with the underflow of the flotation machine is concentrate. Its grade and recovery rate are shown in Table 8.

[0138] The method for preparing modified corn starch is as follows:

[0139] (1) Corn starch was ground using a roller mill at a roller speed of 1200 rpm and a grinding time of 50 min to increase its surface area.

[0140] (2) The ground corn starch and acetamide were mixed in a mass ratio of 4:1 and then dissolved in epichlorohydrin, wherein the mass ratio of the starch and acetamide mixture to epichlorohydrin was 100:6.

[0141] (3) Mix corn starch, acetamide and epichlorohydrin evenly and feed them into the plasma reactor, and ensure that they are evenly distributed in the reactor;

[0142] (4) The plasma reactor uses hydrogen pressurized plasma jet to process corn starch; the plasma reactor pressure is 0.8MPa, the temperature is controlled at 70℃, the jet time is 5min, and the power is 800W.

[0143] (5) The corn starch after washing with ethanol is used to remove unreacted acetamide and epichlorohydrin. After drying at low temperature, modified corn starch can be obtained.

[0144] Table 8. Grade and recovery rate of concentrate and tailings obtained in Example 8

[0145] Concentrate 60.13 33.82 Tailings 12.47 66.18 total 28.59 100

[0146] Comparative Example 1

[0147] A method for selective dissociation and jet capture of iron minerals in iron tailings specifically includes the following steps:

[0148] Step 1. Feed the high-silicon iron tailings with a TFe grade of 24.52% and a particle size of -38μm of 70% into the mixing tank and adjust the slurry concentration to 35%.

[0149] Step 2. Feed the slurry prepared in Step 1 into the abrasive mill and grind it under the conditions of media size of 6 mm, stirring shaft speed of 1000 rpm, media filling rate of 25%, and unit throughput of 40 L / h to obtain the grinding product.

[0150] Step 3. The grinding product obtained in Step 2 is transported to a jet flotation machine via a slurry pump for the flotation recovery of iron minerals. The operating conditions are a slurry concentration of 40%.

[0151] Step 4. After adding reagents into the jet flotation machine, flotation is carried out. First, the pH of the pulp is adjusted to 11 with 400 g / t NaOH. Then, 700 g / t of depressant and 400 g / t of collector are added in sequence. The depressant is wheat starch and the collector is DZ-1. The frothy product obtained from flotation is tailings, and the concentrate flows out with the underflow of the flotation machine. Its grade and recovery rate are shown in Table 9.

[0152] Table 9 shows the grade and recovery rate of the concentrate and tailings obtained in Comparative Example 1.

[0153] Concentrate 42.01 42.15 Tailings 11.78 57.85 total 24.52 100

[0154] Comparative Example 2

[0155] A method for selective dissociation and jet capture of iron minerals in iron tailings specifically includes the following steps:

[0156] Step 1. Feed the high-silicon iron tailings with a TFe grade of 23.96% and a particle size of -38μm of 80% into the mixing tank and adjust the slurry concentration to 40%.

[0157] Step 2. The slurry prepared in step (1) is pumped into a jet flotation machine for flotation recovery of iron minerals. The operating conditions are: slurry concentration 40% and circulation rate 35m³. 3 / h, inflation volume 6m 3 / h;

[0158] Step 3. After adding reagents into the jet flotation machine, flotation is carried out. First, the pH of the pulp is adjusted to 10 with 300 g / t NaOH. Then, 700 g / t of depressant, 600 g / t of activator, and 500 g / t of collector are added in sequence. The depressant is corn starch, the activator is CaO, and the collectors are TD-2 and DZ-1 with a molar ratio of 1:1. The froth product obtained from flotation is the tailings, and the concentrate flows out with the underflow of the flotation machine. Its grade and recovery rate are shown in Table 10.

[0159] Table 10 shows the grade and recovery rate of the concentrate and tailings obtained in Comparative Example 2.

[0160] Concentrate 36.74 39.28 Tailings 15.69 60.72 total 23.96 100

[0161] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A method for selective dissociation and jet capture of iron minerals in iron tailings, characterized in that, Specifically, the following steps are included: Step 1. Feed the high-silicon iron tailings into the mixing tank and adjust the slurry concentration to 30%~60%; Step 2. Feed the slurry prepared in Step 1 into an abrasive mill for grinding to obtain the ground product; Step 3. The grinding product obtained in Step 2 is transported to a jet flotation machine via a slurry pump for the flotation recovery of iron minerals; Step 4. After adding reagents into the jet flotation machine, the flotation operation is carried out. First, the pH of the pulp is adjusted with a modifier, and then the inhibitor, activator and collector are added in sequence. The froth product on the surface is the tailings, and the concentrate flows out with the underflow of the flotation machine. The inhibitor is a modified starch, selected from one or more of modified cassava starch, modified corn starch, or modified wheat starch, and its dosage is 600~1000 g / t; when multiple inhibitors are selected, the multiple inhibitors are in equal mass ratio. In step 4, the preparation process of the modified starch is as follows: (1) Under the conditions of a roller speed of 800~1200 rpm and a grinding time of 50~100 min, starch is ground using a roller mill to increase its surface area; (2) After grinding the starch and acetamide in a mass ratio of (1~5):1, the mixture is dissolved in epichlorohydrin, wherein the mass ratio of the starch and acetamide mixture to epichlorohydrin is 100: (3~7). (3) Mix starch, acetamide and epichlorohydrin evenly and feed them into the plasma reactor, and ensure that they are evenly distributed in the reactor; (4) The plasma reactor uses hydrogen pressurized plasma jet to process starch; (5) The starch after washing with ethanol is used to remove unreacted acetamide and epichlorohydrin, and the modified starch is obtained after low-temperature drying.

2. The method for selective dissociation and jet capture of iron minerals in iron tailings according to claim 1, characterized in that, In step 1, the TFe grade of the high-silicon iron tailings is 23%~30%, and the proportion of particles with a size of -38 μm is 70%~95%.

3. The method for selective dissociation and jet capture of iron minerals in iron tailings according to claim 1, characterized in that, In step 2, the media size of the sand mill is 3~7 mm, the stirring shaft speed is 1000~2500 rpm, the media filling rate is 25%~40%, and the unit processing capacity is 20~100 L / h.

4. The method for selective dissociation and jet capture of iron minerals in iron tailings according to claim 1, characterized in that, In step 3, the operating conditions for flotation recovery are: pulp concentration 30%~50%, circulation rate 20~50 m³ / h. 3 / h, inflation volume 5~10 m 3 / h.

5. A method for selective dissociation and jet capture of iron minerals in iron tailings according to claim 1, characterized in that, In step 4, the adjusting agent is NaOH, and its dosage is 200~400 g / t, and the pH of the slurry is 9~11.

6. A method for selective dissociation and jet capture of iron minerals in iron tailings according to claim 1, characterized in that, The conditions for treating starch by plasma jet are as follows: plasma reactor pressure is 0.4~1.0 MPa, temperature is controlled at 50~80 ℃, jet time is 3~10 min, and power is 500~1000 W.

7. A method for selective dissociation and jet capture of iron minerals in iron tailings according to claim 1, characterized in that, In step 4, the activator is CaO, and its dosage is 600~800 g / t.

8. A method for selective dissociation and jet capture of iron minerals in iron tailings according to claim 1, characterized in that, In step 4, the collector is one or a combination of TD-2 and DZ-1, and its dosage is 300~800 g / t; when multiple collectors are used, the molar ratio between the multiple collectors is 1:

1.

9. The method for selective dissociation and jet capture of iron minerals in iron tailings according to claim 1, characterized in that, The concentrate obtained by this method has a TFe grade of ≥60% and a recovery rate of ≥30%.

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