Method for preparing iron ore concentrates by recycling copper slag tailings

Abstract

The present invention discloses a method for preparing iron ore concentrates by recycling copper smelting slag tailings, and belongs to the technical field of metallurgy and tailings recycling. In the present invention, copper slag tailings obtained after copper pyrometallurgy and flotation and water are used as raw materials, and low-concentration sulfur dioxide flue gas is used as a leaching agent for leaching of metals such as iron, zinc, copper, arsenic, and silicon in the slag tailings; the leachate is purified step by step through processes such as replacement by metal iron powder and sulfide precipitation control, to separate zinc, copper, arsenic, etc.; a purified solution is mainly composed of FeSO.sub.4 or can be used for producing a ferric salt flocculant; obtained tailings are used to obtain iron ore concentrates through magnetic separation, and the obtained iron ore concentrates can be used for further producing ultra-pure iron ore concentrates.

Claims

1. A method for preparing iron ore concentrates by recycling copper slag tailings, comprising the following steps: (1) purifying and absorbing SO.sub.2 flue gas with a SO.sub.2 concentration of 100-1000 mg/m.sup.3 by using copper slag tailings slurry, discharging the slurry when a concentration of SO.sub.2 at a flue gas outlet is greater than 100 mg/m.sup.3, and conducting filtering; (2) adding iron powder to the filtrate under stirring at room temperature to 80° C., wherein an addition amount of the iron powder is 2-5 times of a theoretical amount thereof for replacement of Cu.sup.2+ and Fe.sup.3+; conducting replacement reaction for 30-120 min; and conducting solid-liquid separation, to obtain copper-containing slag and replacement liquid; (3) adding a sulfiding agent to the replacement liquid for precipitation of zinc and arsenic ions, to obtain zinc-containing slag and iron-containing slurry, wherein an addition amount of the sulfiding agent is 3-8 times of a theoretical amount thereof for precipitation of the zinc and arsenic ions; and (4) placing the filter residue obtained in step (1) in a wet magnetic separation device, conducting magnetic separation in a magnetic field with intensity of 0.05-0.2 T to obtain rough iron ore concentrates and tailings, returning the tailings along an original route of a slag dump for treatment, and further conducting magnetic separation on the rough iron ore concentrates to obtain iron ore concentrates.

2. The method for preparing iron ore concentrates by recycling copper slag tailings according to claim 1, wherein the volume content of O.sub.2 in the SO.sub.2 flue gas is 12-21%, and the flue gas temperature is 20-100° C.

3. The method for preparing iron ore concentrates by recycling copper slag tailings according to claim 1, wherein a solid-to-liquid ratio of copper slag tailings to water in the copper slag tailings slurry is 1:3-1:8.

4. The method for preparing iron ore concentrates by recycling copper slag tailings according to claim 1, wherein a particle size of the iron powder is 45-100 μm, and the mass content of iron in the iron powder is greater than 98%.

5. The method for preparing iron ore concentrates by recycling copper slag tailings according to claim 1, wherein the sulfiding agent is ferrous sulfide or sodium sulfide, and a particle size of the ferrous sulfide is 37-150 μm.

Description

DETAILED DESCRIPTION

(1) The present invention is further described in detail below with reference to embodiments, but the protection scope of the present invention is not limited to the following embodiments.

Embodiment 1

(2) In this embodiment, SO.sub.2 cylinder gas with a purity of 1%, N.sub.2 cylinder gas with a purity of 95%, and air extracted by an air pump were used to accurately prepare simulated flue gas from collected environmental smoke in copper smelting by a mass flowmeter, where a total flow rate was 1200 mL/min, a volume concentration of O.sub.2 is 20%, a concentration of SO.sub.2 is 600 mg/m.sup.3; the flue-gas temperature is 25° C.; and copper slag tailings were from a copper smelting company in Yunnan and composed of the following main components by mass percent: Fe 43.10%, Si 13.6%, Ca 2.3%, Zn 1.4%, Al 1.5%, Cu 0.26%, and As 0.08%.

(3) A method for preparing iron ore concentrates from copper slag tailing slurry includes the following:

(4) (1) Slurry was prepared by the copper slag tailings and water at a solid-liquid ratio g:mL of 1:8, added to a 250 mL bubbling reactor, and kept at 25° C. at 200 rpm by using a magnetic stirrer; the prepared simulated flue gas from collected environmental smoke in copper smelting was introduced into the slurry, and held for 4 s; after reaction, flue gas was discharged after it reached the standard, where when the reaction lasted for 15 h, the outlet flue gas reached more than 100 mg/m.sup.3; and the slurry was filtered to recover the filtrate, and the filter residue was collected.

(5) (2) The filtrate was transferred to a replacement reactor, heated to 55° C., and mechanically stirred (50 rpm); 1.2 g/L reduced iron powder with a particle size of 45 μm and the iron mass content of 99% was added; and after reaction was conducted for 1 h, an obtained solution was filtered, where the filtrate was used in a next step, and the filter residue was mainly composed of copper and was recovered for sale.

(6) (3) The filtrate in step (2) was added to a purification reactor, and mechanically stirred at normal temperature; 9.8 g/L commercially available FeS (effective S content is greater than 36%) with a particle size of 45 μm was added; and after reaction was conducted for 1 h, an obtained solution was filtered, where the filtrate was used in a next step, the filter residue was mainly composed of zinc sulfide and was recovered, and the filtrate was mainly composed of Fe SO.sub.4.

(7) (4) Slurry was prepared by water and the filter residue in step (1) with the mass content of 5%, slowly placed in a wet magnetic separator at normal temperature, and subject to magnetic separation in a magnetic field with intensity of 0.05 T to obtain rough iron ore concentrates and tailings; and the tailings was returned along an original route of a slag dump for treatment, and magnetic separation could be further conducted on the rough iron ore concentrates to obtain iron ore concentrates.

(8) Through this process, the filter residue with the copper content of 45% was obtained by replacement; a concentration of Fe.sup.2+ in the purified filtrate is 21 g/L; the yield of the iron ore concentrates obtained after magnetic separation is 26.40%; and in the iron ore concentrates, the content of iron is 50.81%, the content of Si is 5.16%, and the content of As is 0.07%, reaching the grade 5 standard of magnetic concentrate in the iron ore product standard (GB 32545-2016).

Embodiment 2

(9) In this embodiment, SO.sub.2 cylinder gas with a purity of 1%, N.sub.2 cylinder gas with a purity of 95%, and air extracted by an air pump were used to accurately prepare simulated flue gas from a refining furnace in copper smelting by a mass flowmeter, where a total flow rate was 1200 mL/min, a volume concentration of O.sub.2 is 19%, a concentration of SO.sub.2 is 1000 mg/m.sup.3; the flue-gas temperature is 25° C. Copper slag tailings were from a copper smelting company in Hunan and composed of the following main components by mass percent: Fe 48.60%, Si 12.6%, Ca 2.4%, Zn 1.3%, Al 1.4%, Cu 0.28%, and As 0.07%.

(10) A method for preparing iron ore concentrates from copper slag tailing slurry includes the following:

(11) (1) Slurry was prepared by the copper slag tailings and water at a solid-liquid ratio g:mL of 1:5, added to a 250 mL bubbling reactor, and kept at 30° C. at 300 rpm by using a magnetic stirrer; the prepared simulated flue gas from a refining furnace in copper smelting was introduced into the slurry, and held for 5 s; after reaction, flue gas was discharged after it reached the standard, where when the reaction lasted for 10 h, the outlet flue gas reached more than 100 mg/m.sup.3; and the slurry was filtered to recover the filtrate, and the filter residue was collected.

(12) (2) The filtrate was transferred to a replacement reactor, heated to 60° C., and mechanically stirred (100 rpm); 2.1 g/L reduced iron powder with a particle size of 60 μm and the iron mass content of 99% was added; and after reaction was conducted for 1 h, an obtained solution was filtered, where the filtrate was used in a next step, and the filter residue was mainly composed of copper and was recovered for sale.

(13) (3) The filtrate in step (2) was added to a purification reactor, and mechanically stirred at normal temperature; 12.0 g/L commercially available sodium sulfide (effective S content is greater than 25.2%) was added; and after reaction was conducted for 1 h, an obtained solution was filtered, where the filtrate was used in a next step, the filter residue was mainly composed of zinc sulfide and was recovered, and the filtrate was mainly composed of FeSO.sub.4.

(14) (4) Slurry was prepared by water and the filter residue obtained in step (1) with the mass content of 8%, slowly placed in a wet magnetic separator at normal temperature, and subject to magnetic separation in a magnetic field with intensity of 0.1 T to obtain rough iron ore concentrates and tailings; and the tailings was returned along an original route of a slag dump for treatment, and magnetic separation could be further conducted on the rough iron ore concentrates to obtain iron ore concentrates.

(15) Through this process, the filter residue with the copper content of 55% was obtained by replacement; a concentration of Fe.sup.2+ in the purified filtrate is 20 g/L; the yield of the iron ore concentrates obtained after magnetic separation is 48.40%, and in the iron ore concentrates, the content of iron is 57.21%, the content of Si is 4.16%, and the content of As is 0.06%, reaching the grade 5 standard of magnetic concentrate in the iron ore product standard (GB 32545-2016).

Embodiment 3

(16) In this embodiment, SO.sub.2 cylinder gas with a purity of 1%, N.sub.2 cylinder gas with a purity of 95%, and air extracted by an air pump were used to accurately prepare simulated mixed gas of flue gas from a refining furnace and flue gas from collected environmental smoke in copper smelting by a mass flowmeter, where a total flow rate was 1200 mL/min, a volume concentration of O.sub.2 is 19.5%, a concentration of SO.sub.2 is 800 mg/m.sup.3; the flue-gas temperature is 25° C.; and copper slag tailings were from a copper smelting company in Yunnan and composed of the following main components by mass percent: Fe 41.50%, Si 12.6%, Ca 2.8%, Zn 1.3%, Al 1.4%, Cu 0.28%, and As 0.09%.

(17) A method for preparing iron ore concentrates from copper slag tailing slurry includes the following:

(18) (1) Slurry was prepared by the copper slag tailings and water at a solid-liquid ratio g:mL of 1:3, added to a 250 mL bubbling reactor, and kept at 30° C. at 300 rpm by using a magnetic stirrer; the prepared simulated mixed gas of flue gas from a refining furnace and flue gas from collected environmental smoke in copper smelting was introduced into the slurry, and held for 6 s; after reaction, flue gas was discharged after it reached the standard, where when the reaction lasted for 15 h, the outlet flue gas reached more than 100 mg/m.sup.3; and the slurry was filtered to recover the filtrate, and the filter residue was collected.

(19) (2) The filtrate was transferred to a replacement reactor, heated to 70° C., and mechanically stirred (150 rpm); 1.82 g/L reduced iron powder with a particle size of 75 μm and the iron mass content of 99% was added; and after reaction was conducted for 1 h, an obtained solution was filtered, where the filtrate was used in a next step, and the filter residue was mainly composed of copper and was recovered for sale.

(20) (3) The filtrate in step (2) was added to a purification reactor, and mechanically stirred at normal temperature; 13.58 g/L commercially available FeS (effective S content is greater than 36%) with a particle size of 80 μm was added; and after reaction was conducted for 1 h, an obtained solution was filtered, where the filtrate was used in a next step, the filter residue was mainly composed of zinc sulfide and was recovered, and the filtrate was mainly composed of FeSO.sub.4.

(21) (4) Slurry was prepared by water and the filter residue obtained in step (1) with the mass content of 8%, slowly placed in a wet magnetic separator at normal temperature, and subject to magnetic separation in a magnetic field with intensity of 0.2 T to obtain rough iron ore concentrates and tailings; and the tailings was returned along an original route of a slag dump for treatment, and magnetic separation could be further conducted on the rough iron ore concentrates to obtain iron ore concentrates.

(22) Through this process, the filter residue with the copper content of 58% was obtained by replacement; a concentration of Fe.sup.2+ in the purified filtrate is 25 g/L; the yield of the iron ore concentrates obtained after magnetic separation is 48.40%, and in the iron ore concentrates, the content of iron is 51.21%, the content of Si is 4.36%, and the content of As is 0.06%, reaching the grade 5 standard of magnetic concentrate in the iron ore product standard (GB 32545-2016).

Embodiment 4

(23) In this embodiment, flue gas was mixed gas of flue gas from a refining furnace and flue gas from collected environmental smoke in a copper smelting company in Yunnan, where a total flow rate was 1500 m.sup.3/h, a volume concentration of O.sub.2 is 19.5%, a concentration of SO.sub.2 is 1000 mg/m.sup.3, and the flue-gas temperature is 80° C. Copper slag tailings were from this company and composed of the following main components by mass percent: Fe 40.20%, Si 14.9%, Ca 1.4%, Zn 1.3%, Al 1.8%, Cu 0.29%, and As 0.13%.

(24) A method for preparing iron ore concentrates from copper slag tailing slurry includes the following:

(25) (1) Slurry was prepared by the copper slag tailings and water at a solid-liquid ratio g:mL of 1:4 in a slurry preparation tank, and was pumped into a spray-type desulfurization tower by a slurry pump; flue gas was discharged after being subject to reaction in the desulfurization tower, where when the reaction lasted for 15 h, the outlet flue gas reached more than 100 mg/m.sup.3; and filter pressing was conducted on the slurry in a circulating tank to recover the filtrate, and the filter residue was collected.

(26) (2) The filtrate was transferred to a replacement reaction tank, heated to 80° C., and mechanically stirred (200 rpm); 3.5 g/L reduced iron powder with a particle size of 90 μm and the iron mass content of 99% was added; and after reaction was conducted for 1 h, an obtained solution was filtered, where the filtrate was used in a next step, and the filter residue was mainly composed of copper and was recovered for sale.

(27) (3) The filtrate obtained in step (2) was added to a purification reactor, and mechanically stirred at normal temperature; 12.23 g/L commercially available FeS (effective S content is greater than 36%) with a particle size of 100 μm was added; and after reaction was conducted for 1 h, an obtained solution was filtered, where the filtrate was used in a next step, the filter residue was mainly composed of zinc sulfide and was recovered for sale, and the filtrate was mainly composed of FeSO.sub.4.

(28) (4) Slurry was prepared by water and the filter residue obtained in step (1) with the mass content of 8%, slowly placed in a wet magnetic separator at normal temperature, and subject to magnetic separation in a magnetic field with intensity of 0.1 T to obtain rough iron ore concentrates and tailings; and the tailings was returned along an original route of a slag dump for treatment, and magnetic separation could be further conducted on the rough iron ore concentrates to obtain iron ore concentrates.

(29) Through this process, the filter residue with the copper content of 50% was obtained by replacement; a concentration of Fe.sup.2+ in the purified filtrate is 22 g/L; the yield of the iron ore concentrates obtained after magnetic separation is 50.40%, and in the iron ore concentrates, the content of iron is 50.21%, the content of Si is 4.16%, and the content of As is 0.06%, reaching the grade 5 standard of magnetic concentrate in the iron ore product standard (GB 32545-2016).