Method for enhancing magnetism of sulfur-containing copper separation tailings through microwave treatment

Abstract

The invention relates to a method for enhancing the magnetism of sulfur-containing copper separation tailings by microwave treatment, and belongs to the technical field of resource utilization of the copper separation tailings, the method comprises the following steps: S1, crushing and sieving: crushing the copper separation tailings with the sulfur content of 1%-15% and copper tailings by using a jaw crusher to obtain crushed blocks, the crushed blocks are ground and smashed through a ball mill, and tailings are obtained after screening; and S2, carbon powder and a microwave hot spot exciting agent are added into the tailings, uniform stirring is conducted, the stirring speed is controlled to be 13 rpm, and the stirring time is controlled to be 20 min. Corresponding metal and non-metal elements are selectively heated under a microwave field, roasting of iron minerals in the copper separation tailings can be completed within a short time, iron sulfide minerals and hematite are converted into iron minerals with high ferrous oxide content, the magnetic rate of the tailings is increased, the sulfur content is reduced, the utilization difficulties that the copper separation tailings are weak in magnetism and high in sulfur content are solved, and the utilization rate of the copper separation tailings is increased. And after treatment, a foundation can be provided for comprehensive utilization of the copper separation tailings.

Description

Technical Field

[0001] The invention belongs to the technical field of resource utilization of copper-separation tailings, and particularly relates to a method for enhancing magnetic properties of copper-separation tailings by microwave treatment of sulfur-containing copper-separation tailings. Background Art

[0002] As the main component of mine waste, copper tailings are both a large amount of solid waste and a potential secondary resource. The continuous accumulation of copper tailings not only directly occupies a large amount of land resources, but also the sulfur in them, affected by environmental factors, will slowly cause pollution to the soil, water and air. At the same time, due to mining history, technical means, equipment, management and economic market reasons, many elements and components with reusable value are discarded in copper tailings;

[0003] At present, there are two main ways to comprehensively utilize copper tailings: one is to use them as mine filling. The final tailings after separation are pumped into the filling concentrator for concentration. The concentrated tailings are pumped to the tailings filling system for classification. The classified coarse sand is used as the filling material of the mining field, and a small amount of classified overflow (fine particles) is sent to the tailings pond for storage; the other is to recover useful minerals, and further recover iron concentrate by gravity separation and magnetic separation, but the recovery rate of iron is low;

[0004] At present, the resource utilization of low-sulfur tailings (less than 1%) has been preliminarily realized. However, the sulfur content of copper tailings in many mines is 1% to 4%, and the sulfur content of copper tailings in a few mines is 4% to 12%. The high sulfur content of copper tailings limits its utilization. If copper tailings are used directly as roadbed materials, the sulfur or sulfide in the tailings will gradually oxidize to form sulfates, causing cement-based materials to produce a large amount of calcium sulfonate, while causing problems such as reduced alkalinity due to Ca(OH)2 consumption and deterioration of cement-based material properties.

[0005] In order to effectively recover the low-grade valuable metals in the copper tailings, the reduction roasting-magnetic separation method is usually used. Reduction roasting is mainly used to treat difficult-to-select mineral raw materials such as iron, manganese, nickel, copper, tin, etc. For example, weakly magnetic iron ore is magnetized and roasted to transform weakly magnetic hematite, limonite and goethite into strong magnetic magnetite or γ-hematite, and then the valuable part of the tailings is separated from the gangue minerals by magnetic separation. At present, reduction roasting is mainly carried out in rotary kilns, sintering machines and suspension roasting furnaces, etc., and the regeneration of iron concentrate is completed by the action of reducing agents, and then the iron concentrate and other minerals are selected through grinding and magnetic separation. Summary of the invention

[0006] The purpose of the present invention is to provide a method for microwave treatment of sulfur-containing copper tailings to enhance the magnetic properties of the tailings in order to solve the above problems.

[0007] The present invention achieves the above-mentioned purpose through the following technical scheme: adopting microwave heating roasting instead of traditional heating roasting technology to treat copper tailings, enhance the magnetism of the mineral and reduce the sulfur content, using carbon powder or other carbon-containing materials as reducing agents, mixing with a proper amount of microwave hot spot exciter (such as: the preparation method of the microwave hot spot exciter: copper sulfate, zinc sulfate and a small amount of sulfuric acid are mixed and prepared so that the sulfuric acid content in the liquid mixed solution is 0.5% to 4.0%), selectively heating corresponding metal and non-metal elements under a microwave field, and completing the roasting of iron minerals in the copper tailings in a short time, converting iron sulfide minerals and hematite into iron minerals with a higher ferrous oxide content, improving the magnetic rate of the tailings and reducing the sulfur content, and meeting the subsequent utilization requirements.

[0008] The present invention provides a method for enhancing the magnetic properties of sulfur-containing copper tailings by microwave treatment, comprising the following steps:

[0009] Step S1, crushing and screening: crushing the copper tailings with a sulfur content in the range of 1% to 15% by a jaw crusher to obtain broken blocks, grinding the broken blocks by a ball mill, and then sieving to obtain tailings;

[0010] Step S2, adding carbon powder and microwave hot spot exciter to the tailings, stirring evenly, controlling the stirring speed to 13 rpm, controlling the stirring time to 20 min, agglomerating into spheres or blocks, and loading into a crucible, and occupying 80% of the internal volume of the crucible;

[0011] Among them, the advantages of using microwave activators instead of water are: taking advantage of the characteristics of microwaves with selective heating and thermal sensitivity of chemical reactions, uniform microwave hot spots are formed in the minerals, thus improving the roasting effect;

[0012] The purpose of agglomeration is: microwave roasting of minerals from the inside out ensures that there is a large amount of heat inside the agglomerated minerals during microwave roasting, improves the mineral burn-through rate, and improves the feasibility of mineral magnetization and desulfurization;

[0013] Step S3, placing the crucible in step S2 at the center of the microwave oven, and adjusting the microwave power for roasting;

[0014] Among them, the following reactions mainly occur in the microwave field to generate FeO or Fe2O3:

[0015] 2FeS2+5O2→2FeO+4SO2;

[0016] 4FeS2+11O2→2Fe2O3+8SO2;

[0017] 4FeS+7O2→2Fe2O3+4SO2;

[0018] 3Fe2O3+C→2Fe3O4+CO;

[0019] 3Fe2O3+CO→2Fe2O3+CO2;

[0020] The intermediate phase FeO generated is unstable at 200-550°C and will thermally decompose to form Fe3O4;

[0021] 4FeO→Fe3O4+Fe.

[0022] As a further optimization scheme of the present invention, in step S1, the copper tailings are sieved before heating and roasting to obtain at least 80% of -200 mesh tailings.

[0023] As a further optimization scheme of the present invention, the mass ratio of the tailings, carbon powder and microwave hotspot activator in step S2 is 1:0.01 to 0.018:0.03.

[0024] As a further optimization scheme of the present invention, the specific preparation method of the microwave hotspot exciter in step 2 is:

[0025] (i) Dissolve copper sulfate and zinc sulfate in pure water, mix and stir, control the stirring speed to 2 rpm, and control the stirring time to 10 min; (ii) Add sulfuric acid dropwise to (i); (iii) Determine the contents of Cu2+, Zn2+, and H2SO4, and obtain an acidic liquid containing 50-200 mg / L of Cu2+, 10-50 mg / L of Zn2+, and 0.5%-4.0% of H2SO4.

[0026] As a further optimization scheme of the present invention, the mass ratio of the acid copper, zinc sulfate, pure water and sulfuric acid is 1:1:0.3:0.02.

[0027] As a further optimization scheme of the present invention, the acidic liquid is mixed with the tailings to keep the water content of the tailings sample at 13±1%.

[0028] The beneficial effects of the present invention are as follows: by selectively heating the corresponding metal and non-metal elements under a microwave field, the roasting of iron minerals in the copper tailings can be completed in a short time, and the iron sulfide minerals and hematite can be converted into iron minerals with a higher ferrous oxide content, thereby improving the magnetic rate of the tailings and reducing the sulfur content, thereby solving the difficulty in utilizing the copper tailings with weak magnetism and high sulfur content, and providing a basis for the comprehensive utilization of the copper tailings after treatment. DETAILED DESCRIPTION

[0029] The present application is described in further detail below. It is necessary to point out that the following specific implementation methods are only used to further illustrate the present application and cannot be understood as limiting the scope of protection of the present application. Technicians in this field can make some non-essential improvements and adjustments to the present application based on the above application content.

[0030] 1. Materials

[0031] Unless otherwise specified, the methods used in the present invention are conventional methods known to those skilled in the art, and the reagents and other materials used are commercially available products unless otherwise specified.

[0032] 2. Embodiment

[0033] Example 1

[0034] Weigh 50g of -200 mesh sulfur-containing copper tailings sample (S=13.95%, TFe=25.95%, FeO=7.87% 50g, magnetic rate 30.33%), add 0.5g of carbon powder, add a small amount of liquid acid to adjust the moisture content of the mixed ore to 13.6%, stir evenly, make into a ball, then place in a crucible, heat under the condition of microwave power of 700W, and stop heating after heating and roasting for 25min. Determine the sample after roasting, and obtain a mineral with S=4.45%, TFe=31.98%, FeO=25.12%, and magnetic rate=78.54%.

[0035] Example 2

[0036] Weigh 50g of -200 mesh sulfur-containing copper tailings sample (S=8.12%, TFe=24.13%, FeO=4.92%, magnetic rate=20.39%), add 0.75g of carbon powder, add a small amount of liquid acid to adjust the moisture content of the mixed ore to 12.4%, stir evenly, make into a ball, then place in a crucible, heat under the condition of microwave power of 700W, and stop heating after heating and roasting for 30min. Determine the sample after roasting, and obtain a mineral with S=3.65%, TFe=27.11%, FeO=22.52%, and magnetic rate=83.07%.

[0037] Example 3

[0038] Weigh 50g of -200 mesh sulfur-containing copper tailings sample (S=3.49%, TFe=21.98%, FeO=2.25%, magnetic rate=10.24%), add 0.5g of carbon powder, add a small amount of liquid acid to adjust the moisture content of the mixed ore to 13.6%, stir evenly, make into a ball, then place in a crucible, heat under the condition of microwave power of 700W, and stop heating after heating and roasting for 20min. Determine the sample after roasting, and obtain a mineral with S=1.25%, TFe=23.83%, FeO=18.89%, and magnetic rate=79.27%.

[0039] Example 4

[0040] Weigh 50g of -200 mesh sulfur-containing copper tailings sample (S=13.95%, TFe=25.95%, FeO=7.87%, magnetic rate=30.33%), add 0.6g of carbon powder, add a small amount of liquid acid to adjust the moisture content of the mixed ore to 13.2%, stir evenly, make into a ball, then place in a crucible, heat under the condition of microwave power of 406W, and stop heating after heating and roasting for 25min. Determine the sample after roasting, and obtain a mineral with S=9.73%, TFe=27.37%, FeO=14.38%, and magnetic rate=52.54%.

[0041] Example 5

[0042] Weigh 50g of -200 mesh sulfur-containing copper tailings sample (S=8.12%, TFe=24.13%, FeO=4.92%, magnetic rate 20.39%), add 0.5g of carbon powder, and then add a small amount of liquid acid to adjust the moisture content of the mixed ore to 12.5%, stir evenly, make it into a sphere, and then place it in a crucible, heat it under the condition of microwave power of 406W, stop heating after heating and roasting for 20min, measure the sample after roasting, and obtain a mineral with S=6.36%, TFe=27.98%, FeO=13.9%, and magnetic rate=49.68%.

[0043] Example 6

[0044] Weigh 50g of -200 mesh sulfur-containing copper tailings sample (S=3.49%, TFe=21.98%, FeO=2.25%, magnetic rate=10.24%), add 0.8g of carbon powder, add a small amount of liquid acid to adjust the moisture content of the mixed ore to 13.8%, stir evenly, make into a ball, then place in a crucible, heat under the condition of microwave power of 406W, and stop heating after heating and roasting for 30min. Determine the sample after roasting, and obtain a mineral with S=2.48%, TFe=25.35%, FeO=13.19%, and magnetic rate=52.03%.

[0045] Example 7

[0046] Weigh 50g of -200 mesh sulfur-containing copper tailings sample (S=13.95%, TFe=25.95%, FeO=7.87%, magnetic rate=30.33%), add 0.9g of carbon powder, add a small amount of liquid acid to adjust the moisture content of the mixed ore to 13.2%, stir evenly, make into a ball, then place in a crucible, heat under the condition of microwave power of 567W, and stop heating after heating and roasting for 20min. Determine the sample after roasting, and obtain a mineral with S=6.53%, TFe=28.66%, FeO=20.54%, and magnetic rate=71.67%.

[0047] Example 8

[0048] Weigh 50g of -200 mesh sulfur-containing copper tailings sample (S=8.12%, TFe=24.13%, FeO=4.92%, magnetic rate=20.39%), add 0.64g of carbon powder, add a small amount of liquid acid to adjust the moisture content of the mixed ore to 13%, stir evenly, make into a ball, then place in a crucible, heat under the condition of microwave power of 567W, and stop heating after heating and roasting for 25min. Determine the sample after roasting, and obtain a mineral with S=4.78%, TFe=27.93%, FeO=20.21%, and magnetic rate=72.35%.

[0049] Example 9

[0050] Weigh 50g of -200 mesh sulfur-containing copper tailings sample (S=3.49%, TFe=21.98%, FeO=2.25%, magnetic rate=10.24%), add 0.7g of carbon powder, add a small amount of liquid acid to adjust the moisture content of the mixed ore to 12.2%, stir evenly, make into a ball, then place in a crucible, heat under the condition of microwave power of 567W, and stop heating after heating and roasting for 30min. Determine the sample after roasting, and obtain a mineral with S=1.96%, TFe=27.01%, FeO=19.96%, and magnetic rate=73.90%.

[0051] Comparative Example 1

[0052] A method for treating copper tailings provided in Comparative Example 1 of the present invention is different from that in Example 2 in that:

[0053] No toner added.

[0054] Weigh 50g of -200 mesh sulfur-containing copper tailings sample (S=13.95%, TFe=25.95%, FeO=7.87%, magnetic rate=30.33%), add a small amount of liquid acid, adjust the moisture content of the mixed ore to 13.4%, stir evenly and place in a crucible, heat under the condition of microwave power of 700W, and stop heating after heating and roasting for 30min. Determine the sample after roasting, and obtain a mineral with S=11.83%, TFe=26.17%, FeO=9.03%, and magnetic rate=34.51%.

[0055] Comparative Example 2

[0056] A method for treating copper tailings provided in Comparative Example 1 of the present invention is different from that in Example 2 in that:

[0057] Traditional roasting method.

[0058] Weigh 50g of -200 mesh sulfur-containing copper tailings sample (S=13.95%, TFe=25.95%, FeO=7.87%, magnetic rate=30.33%), add 2g of carbon powder, adjust the moisture of the mixed ore to 13.5% with water, stir evenly and place in a crucible, heat and roast the ore in a muffle furnace, and stop heating after reduction roasting at 950°C for 2h. Determine the roasted sample and obtain a mineral with S=6.36%, TFe=32.08%, FeO=13.67%, and magnetic rate=42.61%.

[0059] It should be noted that, in the above embodiment, the higher the microwave roasting power and the longer the roasting time, the better the sulfur reduction and magnetization effect of the sulfur-containing copper-concentration tailings, and there is no limitation on the content of the sulfur-containing copper-concentration tailings. This indicates that the present invention can achieve good results in sulfur reduction and magnetization of the sulfur-containing copper-concentration tailings through microwave treatment under given reaction conditions.

[0060] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for enhancing the magnetic properties of sulfur-containing copper tailings by microwave treatment, characterized in that: The following steps are involved: Step S1, crushing and screening: crushing the copper tailings with a sulfur content in the range of 1% to 15% by a jaw crusher to obtain broken blocks, grinding the broken blocks by a ball mill, and then sieving to obtain tailings; Step S2, adding carbon powder and microwave hot spot exciter to the tailings, stirring evenly, controlling the stirring speed to 13 rpm, controlling the stirring time to 20 min, agglomerating into spheres or blocks, and loading into a crucible, and occupying 80% of the internal volume of the crucible; Step S3, placing the crucible in step S2 at the center of the microwave oven, and adjusting the microwave power for roasting; Among them, the following reactions mainly occur in the microwave field to generate FeO or Fe2O3: 2FeS2+5O2→2FeO+4SO2; 4FeS2+11O2→2Fe2O3+8SO2; 4FeS+7O2→2Fe2O3+4SO2; 3Fe2O3+C→2Fe3O4+CO; 3Fe2O3+CO→2Fe2O3+CO2; The intermediate phase FeO generated is unstable at 200-550°C and will thermally decompose to form Fe3O4; 4FeO→Fe3O4+Fe.

2. The method for enhancing the magnetic properties of tailings by microwave treatment of sulfur-containing copper tailings according to claim 1, characterized in that: In step S1, the copper tailings are sieved before heating and roasting to obtain at least 80% of -200 mesh tailings.

3. The method for enhancing the magnetic properties of tailings by microwave treatment of sulfur-containing copper tailings according to claim 1, characterized in that: In step S2, the mass ratio of tailings, carbon powder and microwave hotspot activator is 1:0.01-0.018:0.

03.

4. The method for enhancing the magnetic properties of tailings by microwave treatment of sulfur-containing copper tailings according to claim 1, characterized in that: The specific preparation method of the microwave hot spot exciter in step 2 is: (i) Dissolve copper sulfate and zinc sulfate in pure water, mix and stir, control the stirring speed to 2 rpm, and control the stirring time to 10 min; (ii) add sulfuric acid dropwise to (i); (iii) Determine the contents of Cu2+, Zn2+, and H2SO4 to obtain an acidic liquid containing 50-200 mg / L of Cu2+, 10-50 mg / L of Zn2+, and 0.5%-4.0% of H2SO4.

5. The method for enhancing the magnetic properties of tailings by microwave treatment of sulfur-containing copper tailings according to claim 4, characterized in that: The mass ratio of the copper acid, zinc sulfate, pure water and sulfuric acid is 1:1:0.3:0.

02.

6. The method for enhancing the magnetic properties of tailings by microwave treatment of sulfur-containing copper tailings according to claim 4, characterized in that: The acidic liquid is mixed with the tailings to keep the water content of the tailings sample at 13±1%.