US 5,667,555 AGranted

Method for the removal of calcium by products during the production of an iron feedstock

AssigneeMetals Recycling Technologies Corp.

InventorsAllan S. Myerson, Charles A. Burrows, Charles W. Sanzenbacher, Paul R. DiBella

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Abstract

A method for the removal of calcium byproducts created during the production of an iron-based feedstock suitable for use as the feedstock for steel mills, from industrial waste streams containing iron, by treating the waste stream with an ammonium chloride leaching solution, treating the leachant with a soluble ammonium salt in which the negative ion will form an insoluble compound with calcium, and separating the undissolved precipitates comprising iron compounds and calcium compounds from the leachant solution. The undissolved precipitants may be treated further by elevated temperature roasting, resulting in the iron-based feedstocks.

Claims14

Dependent claims

A method for the removal of calcium products during a process for the recovery of zinc and iron from waste streams comprising iron oxides, zinc compounds and calcium constituents, comprising the steps of:

a. preroasting said waste stream at an elevated temperature to produce a preroasted waste stream wherein at least a portion of the iron oxides are reduced to direct reduced iron;
b. treating said preroasted waste stream with an ammonium chloride solution at an elevated temperature to form a solution which comprises dissolved zinc components and dissolved calcium constituents and an undissolved precipitate which comprises direct reduced iron and iron oxide, whereby any direct reduced iron and iron oxide in said waste stream will be contained in said undissolved precipitate and will not go into solution;
c. treating said solution with a stoichiometrically suitable amount of a soluble ammonium salt in which the negative ion of the ammonium salt will form an insoluble compound with the calcium to form a product solution substantially free of calcium products and an undissolved calcium compound precipitate;
and
d. separating said product solution from said undissolved precipitate and said undissolved calcium compound precipitate.

2 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/604,178Filed 21 Feb 1996 · continuation in part
Priority: 15 Jan 1992
Granted: 16 Sep 1997
Term ends: Not estimatedThe source records don’t support an estimate.

Classification14 codes

C22B 7/001
Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or…: dry…
C21B 13/006
Making spongy iron or liquid steel, by direct processes: starting from ores containing non ferrous metallic oxides
C22B 5/10
Dry methods smelting of sulfides or formation of mattes: by solid carbonaceous reducing agents
C22B 7/008
Wet processes: by an alkaline or ammoniacal leaching

Family

Serial820,987Parent of this continuation-in-part · filed 15 Jan 1992
Serial953,645Parent of this continuation-in-part · filed 29 Sep 1992
US 5,208,004 AParent of this continuation-in-part · filed 4 May 1993
Serial238,250Parent of this continuation-in-part · filed 4 May 1994
Serial348,446Parent of this continuation-in-part · filed 2 Dec 1994
Serial360,394Parent of this continuation-in-part · filed 21 Dec 1994
Serial380,950Parent of this continuation-in-part · filed 31 Jan 1995
US 5,582,631 AParent of this continuation-in-part
US 5,571,306 AParent of this continuation-in-part
US 5,464,596 AParent of this continuation-in-part
US 5,667,555 AThis patent

From the US filing history. Foreign family members aren’t listed.