Methods and apparatus for metal recovery from slag

Patent metadata

Field	Value
Publication number	US-10174403-B2
Application number	US-201515537708-A
Country	US
Kind code	B2
Filing date	Dec 14, 2015
Priority date	Dec 19, 2014
Publication date	Jan 8, 2019
Grant date	Jan 8, 2019

Abstract

A method for recovering metal values from a molten slag composition includes atomizing the slag with an oxygen-containing gas in a gas atomization apparatus, to produce solid slag granules. Oxygen in the atomizing gas converts metals to magnetic metal compounds, thereby magnetizing the metal-containing slag granules. These metal-containing slag granules are then magnetically separated. Larger amounts of metals may be removed by passing the molten slag through a pre-settling pan with an adjustable base, and/or discontinuing atomization where the metal content of the slag exceeds a predetermined amount. Solid slag granules produced by atomization may be charged to a recovery unit for recovery of one or more metal by-products. An apparatus for recovering metal values from molten slag includes a gas atomization apparatus, a flow control device for controlling the flow of atomizing gas, a control system, and one or more sensors to detect metal values in the slag.

First claim

What is claimed is:

1. A method for separating a metal-rich fraction from a slag composition, the method comprising:
(a) providing said slag composition in molten form, wherein the slag composition contains one or more metal values;
(b) feeding the molten slag composition to an atomization chamber of a gas atomization apparatus;
(c) feeding a stream of a gas into the atomization chamber through an atomization nozzle, wherein the gas contains oxygen;
(d) atomizing the molten slag composition with the stream of gas in the atomization chamber to disperse and solidify the molten slag composition to form solid slag granules,
wherein the gas contains oxygen in a sufficient concentration to convert at least a portion of the one or more metal values to one or more magnetic compounds during the atomizing of the molten slag composition;
wherein the magnetic compounds comprise one or more spinel structures having the general formula AB 2 O 4 , wherein A is a divalent cation and B is a trivalent cation;
wherein the presence of said magnetic compounds in sufficient concentrations in a first fraction of the solid slag granules renders the granules of the first fraction sufficiently magnetic to permit them to be separated from the remainder of the solid slag granules by magnetic means;

(e) controlling the partial pressure of oxygen in the gas so that the molten slag composition has a composition which lies in thea spinel primary crystallization phase field; and
(f) magnetically separating the first fraction from thea remainder of the solid slag granules.

2. The method of claim 1 , wherein the one or more metal values are selected from one or more members of the group consisting of:
entrained non-magnetic metals or alloys, and chemically dissolved metals or alloys.

3. The method of claim 1 , wherein the gas comprises air.

4. The method of claim 1 , further comprising the step of tapping the molten slag composition from a metallurgical furnace and transporting the molten slag composition from the furnace to the gas atomization apparatus while maintaining the slag composition in its molten state.

5. The method of claim 4 , further comprising the step of returning the first fraction of the solid slag granules to the metallurgical furnace for re-smelting.

Assignees

• Hatch Ltd
• Hatch Ltd

Inventors

• Mostaghel Sina
• Cramer Matthew H
• Faucher Santiago
• So Lai Chi
• Nell Johannes

Classifications

• G01N33/205

  in liquid state, e.g. molten metals · CPC title

• G01N33/2028

  Metallic constituents · CPC title

• C22B7/04 Primary

  Working-up slag · CPC title

• C22B7/005

  Separation by a physical processing technique only, e.g. by mechanical breaking · CPC title

• C01B13/34

  by oxidation or hydrolysis of sprayed or atomised solutions · CPC title