Method of separating and recovering iron from waste non-ferrous slag discharged from process for smelting of non-ferrous metals, including copper, zinc and lead by physical and chemical separation technique

Patent metadata

Field	Value
Publication number	US-9334548-B2
Application number	US-201213989452-A
Country	US
Kind code	B2
Filing date	Oct 18, 2012
Priority date	Sep 7, 2012
Publication date	May 10, 2016
Grant date	May 10, 2016

Abstract

The present invention provides a method of separating and recovering iron from a waste non-ferrous slag, generated in a process for smelting of non-ferrous metals, including copper, zinc and lead, in which a reducing agent and a reaction catalyst are added to the crushed waste non-ferrous slag, and the mixture is subjected to a reduction reaction, thereby converting amorphous iron oxides, bound to alumina, calcium oxide, magnesium oxide, silica, and the like in the waste non-ferrous slag, to crystalline iron (Fe) and iron carbide (Fe 2 C); the resulting material is crushed to separate iron and iron carbide obtained by the reduction reaction from components such as alumina, calcium oxide, magnesium oxide, silica, and the like; the crushed material is separated into fractions by particle size; and the fractions are subjected to wet magnetic separation and dry magnetic separation to separate and recover magnetic iron concentrates from the fractions.

First claim

The invention claimed is:

1. A method of separating and recovering iron from a waste non-ferrous slag, discharged from a process for smelting of non-ferrous metals, including copper, zinc and lead, by physical and chemical separation, the method comprising the steps of:
(a) crushing the waste non-ferrous slag;
(b) mixing the waste non-ferrous slag, crushed in step (a), with carbon as a reducing agent and calcium carbonate (CaCO 3 ) as a reaction catalyst, in amounts, based on the weight of the waste non-ferrous slag, of 5-40 wt % of carbon and 3-20 wt % of calcium carbonate (CaCO 3 ), charging the mixture into an electric furnace to a thickness of 5-15 cm, and subjecting the charged mixture to a reduction reaction at a temperature of 1000-1300° C. for 30-90 minutes while passing air through the electric furnace at a rate of 0.5-1.5 l/min, thereby converting amorphous iron oxides, bound to alumina (Al 2 O 3 ), calcium oxide (CaO), magnesium oxide (MgO), silica (SiO 2 ), zinc oxide (ZnO), copper oxide (CuO) and lead oxide (PbO) in the waste non-ferrous slag, to crystalline iron (Fe) and iron carbide (Fe 2 C);
(c) crushing the material resulting from step (b) to separate iron (Fe) and iron carbide (Fe 2 C) obtained in step (b) from components such as alumina (Al 2 O 3 ), calcium oxide (CaO), magnesium oxide (MgO), silica (SiO 2 ), zinc oxide (ZnO), copper oxide (CuO) and lead oxide (PbO);
(d) separating the crushed material, obtained in step (c), into fractions according to particle size; and
(e) subjecting the fractions, obtained in step (d), to wet magnetic separation and dry magnetic separation, to separate magnetic iron concentrates from the fractions, and mixing the magnetic iron concentrates with each other.

2. The method of claim 1 , wherein the waste non-ferrous slag is crushed in step (a) to a particle size of 150-203 μm in diameter.

3. The method of claim 1 , wherein step (c) is performed by crushing the material obtained in step (b) to a particle size of 61-104 μm in diameter.

4. The method of claim 1 , wherein step (d) is performed by separating the crushed material, obtained in step (c), into a fraction having a particle size of 61-74 μm and a fraction having a particle size of 75-104 μm.

5. The method of claim 1 , wherein step (e) is performed by subjecting a faction having a particle size of 61-74 μm to wet magnetic separation at a magnetic field strength of 2500-3500 Gauss to separate crystalline iron and iron carbide as magnetic materials, subjecting a fraction having a particle size of 75-104 μm to dry magnetic separation at a magnetic field strength of 200-400 Gauss to separate crystalline iron and iron carbide as magnetic materials, and mixing the obtained magnetic materials with each other.

6. A method of separating and recovering iron from a waste non-ferrous slag, discharged from a process for smelting of non-ferrous metals, including copper, zinc and lead, by physical and chemical separation, the method comprising the steps of:
(a) crushing the waste non-ferrous slag;
(b) mixing the waste non-ferrous slag, crushed in step (a), with carbon as a reducing agent and calcium carbonate (CaCO 3 ) as a reaction catalyst, and subjecting the mixture to a reduction reaction, thereby converting amorphous iron oxides, bound to alumina (Al 2 O 3 ), calcium oxide (CaO), magnesium oxide (MgO), silica (SiO 2 ), zinc oxide (ZnO), copper oxide (CuO) and lead oxide (PbO) in the waste non-ferrous slag, to crystalline iron (Fe) and iron carbide (Fe 2 C);
(c) crushing the material resulting from step (b) to separate iron (Fe) and iron carbide (Fe 2 C) obtained in step (b) from components such as alumina (Al 2 O 3 ), calcium oxide (CaO), magnesium oxide (MgO), silica (SiO 2 ), zinc oxide (ZnO), copper oxide (CuO) and lead oxide (PbO);
(d) separating the crushed material, obtained in step (c), into fractions according to particle size; and
(e) subjecting the fractions, obtained in step (d), to wet magnetic separation and dry magnetic separation, to separate magnetic iron concentrates from the fractions, and mixing the magnetic iron concentrates with each other,

wherein step (e) is performed by subjecting a faction having a particle size of 61-74 μm to wet magnetic separation at a magnetic field strength of 2500-3500 Gauss to separate crystalline iron and iron carbide as magnetic materials, subjecting a fraction having a particle size of 75-104 μm to dry magnetic separation at a magnetic field strength of 200-400 Gauss to separate crystalline iron and iron carbide as magnetic materials, and mixing the obtained magnetic materials with each other.

Assignees

• Korea Inst Geoscience & Minera

Inventors

• Kim Byung-Su
• Lee Jae Chun
• Jeong Soo Bok
• Shin Doyun

Classifications

• C22B7/04 Primary

  Working-up slag · CPC title

• C22B1/005

  Preliminary treatment of scrap (C22B1/02 - C22B1/26 take precedence) · CPC title

• Y02P10/212

  Cross-Sectional Technologies · mapped topic

• C22B5/00 Primary

  General methods of reducing to metals · CPC title

• Y02P10/20

  Recycling · CPC title