Treatment method of copper flotation tailings, slag wool

Abstract

The application provides a copper flotation tailings treatment method. The treatment method comprises the following steps: smelting copper flotation tailings, red mud, a reducing agent and an additive according to a stoichiometric ratio to obtain CaO-SiO2-Al2O3-MgO slag type molten slag, molten iron and dust; and continuously homogenizing the molten slag to obtain slag wool. The application recovers iron and zinc resources in the copper flotation tailings and iron resources in the red mud, and also prepares high-value slag wool without any new solid waste output, thereby achieving the beneficial effects of large-scale treatment of the copper flotation tailings and the red mud, efficient comprehensive recovery of valuable metals in the copper flotation tailings and the red mud, and full utilization of the slag.

Description

Technical Field

[0001] This invention relates to the field of copper smelting technology, and more specifically, to a method for treating copper flotation tailings and slag wool. Background Technology

[0002] Copper smelting processes generate a large amount of copper smelting slag, containing 0.8–3 wt% copper. The copper in this smelting slag is typically recovered. Currently, most copper smelters use slow-cooling flotation processes to treat this smelting slag, obtaining slag concentrate and flotation tailings. While some copper is recovered from the smelting slag, a large amount of copper flotation tailings remains, causing land occupation, resource waste, and environmental pollution. Furthermore, existing technologies for recovering these tailings have the following problems: some technologies are limited to iron recovery with low iron recovery rates and do not address the comprehensive utilization of the tailings. However, copper flotation tailings contain elements such as zinc, lead, arsenic, and silicon in addition to copper and iron, and existing technologies fail to comprehensively consider the orientation and distribution of these elements during the ironmaking process. Therefore, how to effectively treat this portion of copper flotation tailings (whose main components include silicon dioxide, magnetic iron, and fir olivine, and minor components include zinc oxide and lead oxide) to maximize the utilization of its valuable elements is a technical problem that needs to be solved. Summary of the Invention

[0003] The main objective of this invention is to provide a method for treating copper flotation tailings and slag wool, so as to solve the problem that the existing technology cannot effectively treat copper flotation tailings.

[0004] To achieve the above objectives, according to one aspect of the present invention, a method for treating copper flotation tailings is provided. The method includes: mixing copper flotation tailings, red mud, reducing agent, and additives in a stoichiometric ratio and smelting them to obtain slag with a slag type of CaO-SiO2-Al2O3-MgO, molten iron, and flue dust. The slag includes the following components: 36-39 wt% SiO2, 10-14 wt% Al2O3, 0.6-1.2 wt% Fe2O3, 38-42 wt% CaO, 6-10 wt% MgO, and 0-0.7 wt% S; and further homogenizing the slag to obtain slag wool.

[0005] Further, the reducing agent is selected from one or more of anthracite, bituminous coal, lignite, coke or graphite; preferably, the auxiliary agent is selected from one or more of dolomite, limestone or lime; more preferably, the auxiliary agent is selected from dolomite and limestone.

[0006] Furthermore, the smelting temperature is 1400–1600℃ and the processing time is 0.5–5h; preferably, the smelting temperature is 1500–1600℃ and the processing time is 1–3h.

[0007] Furthermore, the smelting is carried out in an induction furnace, a submerged arc furnace, an electric furnace, or a side-blown smelting furnace; preferably, the smelting is carried out in a submerged arc furnace.

[0008] Furthermore, after mixing and before smelting, the treatment method also includes a step of shaping the mixed material; preferably, a binder is added to the mixed material to shape it into spherical mixtures; preferably, the average diameter of the spherical mixtures is 0.3 to 5 cm; preferably, the binder is selected from one or more of clay, water glass, or corn starch; preferably, the amount of binder used is 0.01 to 0.15% of the total weight of copper flotation tailings, red mud, reducing agent, and additives.

[0009] Furthermore, after smelting, the processing method also includes casting the molten iron into ingots to obtain bread iron.

[0010] Furthermore, after smelting, the treatment method also includes the following post-treatment steps for the flue dust: the flue dust is subjected to secondary combustion and then settled to obtain secondary combustion flue dust and secondary combustion flue gas with a particle size ≥5mm; the secondary combustion flue dust is returned to the smelting process for recycling; the secondary combustion flue gas is passed through a waste heat boiler to recover waste heat, and then collected by a dust collector to obtain zinc-rich flue dust.

[0011] Furthermore, the water content of the copper flotation tailings and red mud is independently <15wt%.

[0012] Furthermore, the homogenization treatment temperature is 1400–1600℃, and the treatment time is 0.3–3h.

[0013] To achieve the above objectives, according to one aspect of the present invention, slag wool obtained from the aforementioned copper flotation tailings treatment method is provided.

[0014] This invention, while recovering iron and zinc resources from copper flotation tailings and iron resources from red mud, also produces high-value slag wool without generating any new solid waste. It achieves the beneficial effects of large-scale treatment of copper flotation tailings and red mud, efficient and comprehensive recovery of valuable metals from these materials, and full utilization of the slag. This solves the problems of stockpiling copper flotation tailings and red mud, and the ineffective recovery of valuable metals (such as iron and zinc) from these materials. Furthermore, the equipment and process described in this invention are simple, and those skilled in the art can select appropriate smelting equipment and processes based on regional energy advantages. Therefore, this invention effectively achieves efficient, high-value, and full utilization of both copper flotation tailings and red mud. Attached Figure Description

[0015] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0016] Figure 1 A flowchart of a method for treating copper flotation tailings according to one embodiment of the present invention is shown. Detailed Implementation

[0017] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0018] As described in the background section of this invention, there is a technical problem in the prior art that it cannot effectively treat copper flotation tailings. To solve this problem, this invention provides a method for treating copper flotation tailings. Figure 1 As shown, the processing method includes: mixing copper flotation tailings, red mud, reducing agent and additives in stoichiometric ratio and smelting to obtain slag of CaO-SiO2-Al2O3-MgO type, molten iron and dust, and the slag includes the following components: 36-39 wt% SiO2, 10-14 wt% Al2O3, 0.6-1.2 wt% Fe2O3, 38-42 wt% CaO, 6-10 wt% MgO, and 0-0.7 wt% S; and continuing to homogenize the slag to obtain slag wool.

[0019] This invention involves first smelting copper flotation tailings, red mud, reducing agent, and additives according to a stoichiometric ratio to obtain a CaO-SiO2-Al2O3-MgO slag, molten iron, and flue dust. The slag is then homogenized to obtain slag wool, thus achieving the beneficial effect of efficiently treating copper flotation tailings. To further illustrate the beneficial effects of this invention, the raw materials used in the above preparation method are described as follows:

[0020] Firstly, red mud is a solid, powdery waste product generated after extracting alumina from bauxite. Approximately 0.6 to 2.5 tons of red mud are produced for every ton of alumina produced. Its main components include silicon dioxide, aluminum oxide, calcium oxide, and ferric oxide. The large volume of red mud produced leads to problems such as extensive stockpiling and difficulty in utilization, hindering the sustainable development of the aluminum smelting industry. Therefore, reducing the volume and recycling red mud is an urgent issue that needs to be addressed. This application, while treating the aforementioned copper flotation tailings, also co-processes red mud. Using red mud as a conditioning agent, it combines the silicon dioxide in the copper flotation tailings with the aluminum oxide, calcium oxide, and silicon dioxide in the red mud, along with additives, to perform online conditioning during the smelting process, thereby producing a CaO-SiO2-Al2O3-MgO slag.

[0021] Secondly, copper flotation tailings also contain 30-50 wt% iron, 0.5-4 wt% zinc, and trace amounts of lead. Zinc and lead mainly exist in oxide form, while iron primarily exists as magnetic iron and fir olivine. This invention, by adding a reducing agent, reduces the magnetic iron and fir olivine to form molten iron after smelting. The molten iron settles and separates from the slag. Since the copper flotation tailings are obtained after mineral processing and have a low copper content, the molten iron obtained from smelting has a very low copper content. It can not only be directly used for iron smelting but also as a raw material for scrap steel or pig iron smelting (while iron concentrate from conventional reduction magnetic separation can only be used for iron smelting). Simultaneously, the zinc and lead oxides are reduced to metallic states and volatilize into the flue dust, which, after further processing, produces high-grade zinc-rich flue dust.

[0022] Thus, the iron content in the CaO-SiO2-Al2O3-MgO slag obtained by this invention can be reduced to below 0.7 wt%, and the zinc and lead content can be reduced to below 0.001 wt%. Based on this, this invention can reduce the cost of preparing slag wool slagging agent from copper flotation tailings, and the prepared slag wool can be used directly, avoiding the drawback of requiring further processing as a raw material for cement and other building materials. Moreover, the value of slag wool is far higher than that of cement and other building materials.

[0023] In summary, this invention, while recovering iron and zinc resources from copper flotation tailings and iron resources from red mud, also produces high-value slag wool without generating any new solid waste. It achieves the beneficial effects of large-scale treatment of copper flotation tailings and red mud, efficient and comprehensive recovery of valuable metals from these materials, and full utilization of the slag. This solves the problems of stockpiling copper flotation tailings and red mud, and the ineffective recovery of valuable metals (such as iron and zinc) from these materials. Furthermore, the equipment and process described in this invention are simple, and those skilled in the art can select appropriate smelting equipment and processes based on regional energy advantages. Therefore, this invention effectively achieves efficient, high-value, and full utilization of both copper flotation tailings and red mud.

[0024] Additionally, in one optional embodiment, the CaO-SiO2-Al2O3-MgO slag-type molten slag can continue to be discharged intermittently or continuously via a siphon, and then flow into a homogenizing and heat-preserving furnace via a chute. After adjusting the uniformity of the composition in the furnace, it is then passed through a slag wool preparation device to prepare slag wool.

[0025] Furthermore, the copper flotation tailings described in this application comprise the following components: 30–50 wt% Fe, 20–40 wt% SiO2, 0.3–3 wt% Pb, 0.5–6 wt% Zn, 0.2–5 wt% MgO, 0.2–5 wt% CaO, 0.2–5 wt% Al2O3, and the balance being impurities (e.g., copper compounds). The red mud comprises the following components: 5–20 wt% Al2O3, 30–70 wt% Fe, 2–15 wt% SiO2, 0.5–50 wt% CaO, 0.5–5 wt% MgO, and the balance being impurities (e.g., sodium oxides, loss on ignition).

[0026] In a preferred embodiment, the moisture content of the copper flotation tailings and red mud is independently <15wt%. Based on this, the present invention can control the production of CaO-SiO2-Al2O3-MgO slag, molten iron, and zinc-rich flue dust with lower energy consumption and lower cost, resulting in higher solid waste treatment efficiency.

[0027] To further improve the reduction effect, the reducing agent is preferably selected from one or more of anthracite, bituminous coal, lignite, coke, or graphite. To obtain slag with a slag type of CaO-SiO2-Al2O3-MgO more efficiently, in a preferred embodiment, the additive is selected from one or more of dolomite, limestone, or lime; more preferably, the additive is selected from dolomite and limestone.

[0028] To further improve smelting efficiency, the preferred smelting temperature is 1400–1600℃ (e.g., 1400℃, 1450℃, 1500℃, 1550℃, or 1600℃), and the processing time is 0.5–5 hours (e.g., 0.5 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, or 5 hours). Based on this, the present invention can better control the slag, molten iron, and flue dust of the CaO-SiO2-Al2O3-MgO slag type, thereby achieving the beneficial effects of large-scale treatment of copper flotation tailings and red mud, efficient comprehensive recovery of valuable metals from copper flotation tailings and red mud, and full utilization of slag. Preferably, the smelting temperature is 1500–1600℃, and the processing time is 1–3 hours.

[0029] In some alternative embodiments, smelting can be carried out in any of an induction furnace, a submerged arc furnace, an electric furnace, or a side-blown smelting furnace. The heat source for smelting can be electric heating or heat provided by the combustion of natural gas, coal, coal gas, coal gasification, etc., with oxygen or oxygen-enriched air. More preferably, smelting is carried out in a submerged arc furnace, based on which the resulting zinc-rich flue dust has a higher grade.

[0030] To prevent the powder from directly entering the furnace and affecting the zinc grade in the flue gas, in a preferred embodiment, the treatment method further includes a step of shaping the mixed material after mixing and before smelting. Preferably, a binder is added to the mixed material for shaping to obtain spherical mixtures with an average diameter of 0.3–5 cm. The binder is selected from one or more of clay, water glass, or corn starch. More preferably, the amount of binder used is 0.01–0.15% of the total weight of copper flotation tailings, red mud, reducing agent, and additives.

[0031] In a preferred embodiment, after smelting, the processing method further includes casting the molten iron into ingots to obtain bread iron. Specifically, the molten iron produced from smelting can be intermittently discharged and then cast into ingots in a casting machine to obtain bread iron. Simultaneously, after smelting, the processing method also includes a flue gas post-treatment step: the flue gas undergoes secondary combustion in a secondary combustion chamber and then settles to obtain secondary combustion flue gas (large particulate flue gas) with a particle size ≥5mm and secondary combustion flue gas; the large particulate flue gas is returned to the smelting process as recycled material; the secondary combustion flue gas is then collected by a waste heat boiler after recovering waste heat, and then by a dust collector (baghouse dust collector) to obtain zinc-rich flue gas. During the smelting process, to improve the reduction rate of iron, the main component of the flue gas is CO. This invention allows such smelting flue gas to continue secondary combustion in a secondary combustion chamber and settle there, obtaining large particulate flue gas, which is then transported to a return material bin and can be reused in the system for smelting, improving waste utilization. Meanwhile, the zinc and lead volatilized in the flue gas after secondary combustion are further oxidized into lead and zinc oxides. After the waste heat is recovered by the waste heat boiler, the flue gas is collected by bag filter dust to obtain zinc-rich dust, which contains 40-70% zinc and 5-20% lead. The residual flue gas after the dust collector is further treated to obtain qualified flue gas for discharge.

[0032] To obtain slag wool with better application performance, the preferred homogenization treatment temperature is 1400–1600℃, and the treatment time is 0.3–3h.

[0033] This invention also provides slag wool obtained from the aforementioned copper flotation tailings treatment method. Based on the reasons stated above, the slag wool obtained in this application has superior performance and can be directly used as a product.

[0034] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0035] Example 1

[0036] The composition of the copper flotation tailings is as follows: 40.63 wt% Fe, 33 wt% SiO2, 1 wt% CaO, 1.7 wt% MgO, 2.51 wt% Zn, 0.46 wt% Pb, and the balance being impurities.

[0037] The composition of the red mud is as follows: 51 wt% Fe, 5 wt% SiO2, 2.6 wt% CaO, 1.05 wt% MgO, 15 wt% Al2O3 and balance impurities.

[0038] Copper flotation tailings, red mud, limestone, anthracite, and dolomite were mixed in a weight ratio of 100:50:56:35:23 and pelletized (corn starch was used as a binder at 1% of the weight of the copper flotation tailings, and the average diameter of the pellets was 1.5 cm). The pellets were then added to a submerged arc furnace and smelted using electric heat at 1500℃ for 2 hours. After smelting, molten slag of the CaO-SiO2-Al2O3-MgO type, molten iron, and flue dust were obtained.

[0039] The slag mainly consists of the following components: 36.66 wt% SiO2, 12.01 wt% Al2O3, 0.85 wt% Fe2O3, 38.86 wt% CaO, 7.9 wt% MgO, 0.008 wt% S, and the balance being impurities.

[0040] The iron content in the slag decreased to 0.6 wt%, the zinc content decreased to 0.0005 wt%, and the lead content decreased to 0.0002 wt%.

[0041] The molten slag is intermittently discharged and then flows into a homogenizing furnace via a chute. After adjusting the composition homogenization in the furnace (the homogenization treatment temperature is 1450℃ and the treatment time is 1 hour), slag wool is prepared using slag wool preparation equipment. The yield of slag wool is 95%.

[0042] Molten iron produced by smelting is intermittently discharged and cast into ingots to obtain bread iron.

[0043] The flue gas is subjected to secondary combustion and then settled to obtain secondary combustion flue gas and particles with a diameter ≥5 mm. The secondary combustion flue gas is returned to the smelting process for recycling. The secondary combustion flue gas is then passed through a waste heat boiler to recover waste heat, and then collected by a bag filter to obtain zinc-rich flue gas. The zinc-rich flue gas contains 60 wt% zinc and 10 wt% lead.

[0044] Example 2

[0045] The only difference from Example 1 is that in the side-blown furnace, oxygen-enriched gas with a mass concentration of 70-100% is used as the combustion air, and natural gas is used as fuel to provide heat for smelting.

[0046] After smelting, the iron content in the slag decreased to 0.6 wt%, the zinc content to 0.0005 wt%, and the lead content to 0.0002 wt%. The yield of slag wool was 93%. The zinc-rich flue dust contained 50 wt% zinc and 7 wt% lead.

[0047] Compared to the submerged arc furnace process, the zinc and lead content in the final zinc-rich flue dust obtained by the side-blown furnace process is slightly lower.

[0048] Example 3

[0049] The only difference from Example 1 is that the smelting temperature is 1450°C.

[0050] After smelting, the iron content in the slag decreased to 0.8 wt%, the zinc content to 0.0007 wt%, and the lead content to 0.0005 wt%. The yield of slag wool was 94%. The zinc-rich flue dust contained 58 wt% zinc and 10.5 wt% lead.

[0051] Example 4

[0052] The only difference from Example 1 is that it does not include the step of molding the mixed material.

[0053] After smelting, the iron content in the slag decreased to 1 wt%, the zinc content to 0.001 wt%, and the lead content to 0.0005 wt%. The yield of slag wool was 88%. The zinc-rich flue dust contained 45 wt% zinc and 5.6 wt% lead.

[0054] Not using mixed materials for molding will result in a higher dust rate, lower yield, and poor reactivity.

[0055] Example 5

[0056] The only difference from Example 1 is that the smelting temperature is 1400°C.

[0057] After smelting, the iron content in the slag decreased to 3 wt%, the zinc content to 0.5 wt%, and the lead content to 0.3 wt%. The yield of slag wool was 75%. The zinc-rich flue dust contained 37 wt% zinc and 5 wt% lead.

[0058] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for treating copper flotation tailings, characterized in that, The processing method includes: The copper flotation tailings, red mud, reducing agent, and additives are mixed in stoichiometric ratios and smelted to obtain slag with a slag type of CaO-SiO2-Al2O3-MgO, molten iron, and flue dust. The slag comprises the following components: 36-39 wt% SiO2, 10-14 wt% Al2O3, 0.6-1.2 wt% Fe2O3, 38-42 wt% CaO, 6-10 wt% MgO, and 0-0.7 wt% S. The smelting process is carried out at a temperature of 1500-1600℃ for 1-3 hours. The additives are selected from one or more of dolomite, limestone, or lime. The slag is further homogenized to obtain slag wool.

2. The method for treating copper flotation tailings according to claim 1, characterized in that, The reducing agent is selected from one or more of anthracite, bituminous coal, lignite, coke, or graphite.

3. The method for treating copper flotation tailings according to claim 1, characterized in that, The additives are selected from dolomite and limestone.

4. The method for treating copper flotation tailings according to claim 1, characterized in that, The smelting is carried out in an induction furnace, a submerged arc furnace, an electric furnace, or a side-blown smelting furnace.

5. The method for treating copper flotation tailings according to claim 4, characterized in that, The smelting is carried out in a submerged arc furnace.

6. The method for treating copper flotation tailings according to any one of claims 1 to 5, characterized in that, After the mixing and before the smelting, the processing method further includes a step of shaping the mixed material.

7. The method for treating copper flotation tailings according to claim 6, characterized in that, A binder is added to the mixed material to perform the molding process, resulting in a spherical mixture.

8. The method for treating copper flotation tailings according to claim 7, characterized in that, The average diameter of the spherical mixture is 0.3~5cm.

9. The method for treating copper flotation tailings according to claim 7, characterized in that, The binder is selected from one or more of clay, water glass, or corn starch.

10. The method for treating copper flotation tailings according to claim 7, characterized in that, The amount of the binder is 0.01 to 0.15% of the total weight of the copper flotation tailings, the red mud, the reducing agent, and the additives.

11. A method for treating copper flotation tailings according to any one of claims 1 to 5, characterized in that, After the smelting, the processing method further includes the step of casting the molten iron into ingots to obtain bread iron.

12. The method for treating copper flotation tailings according to any one of claims 1 to 5, characterized in that, After the smelting, the processing method further includes the following post-treatment steps for the flue dust: The soot is subjected to secondary combustion and then settled to obtain secondary combustion soot and secondary combustion flue gas with a particle size ≥5mm. The secondary combustion flue gas is returned to the smelting process for recycling; The secondary combustion flue gas is passed through a waste heat boiler to recover waste heat, and then collected by a dust collector to obtain zinc-rich flue gas dust.

13. The method for treating copper flotation tailings according to claim 1, characterized in that, The water content of the copper flotation tailings and the red mud is each <15wt%.

14. The method for treating copper flotation tailings according to claim 1, characterized in that, The homogenization process is carried out at a temperature of 1400~1600℃ for 0.3~3h.

15. A slag wool obtained by the method for treating copper flotation tailings according to any one of claims 1 to 14.

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