System and method for control of a copper melting furnace

Patent metadata

Field	Value
Publication number	US-9873926-B2
Application number	US-201515317684-A
Country	US
Kind code	B2
Filing date	Oct 9, 2015
Priority date	Oct 10, 2014
Publication date	Jan 23, 2018
Grant date	Jan 23, 2018

Abstract

A method and system of controlling a melting process of copper in a copper melting furnace including measuring at least one furnace parameter, wherein the at least one furnace parameter includes one or both of a furnace temperature and a furnace exhaust oxygen concentration, calculating a first rate of change of the furnace parameter over a first time period, calculating a second rate of change of the furnace parameter over a second time period at least a portion of which occurs after the first time period, comparing the first rate of change with the second rate of change, and indicating substantial completion of a process phase in the furnace when the second rate of change deviates by a predetermined threshold percentage from the first rate of change.

First claim

The invention claimed is:

1. A method of controlling a melting process of copper in a copper melting furnace, comprising:
introducing a flow of an oxidizing agent into a furnace to begin an oxidation phase;
measuring at least one furnace parameter, wherein the at least one furnace parameter comprises both of a furnace temperature and a furnace exhaust oxygen concentration;
calculating a first rate of change of the furnace parameter over a first time period;
calculating a second rate of change of the furnace parameter over a second time period at least a portion of which occurs after the first time period;
comparing the first rate of change with the second rate of change;
indicating substantial completion of the oxidation phase when the second rate of change deviates by a predetermined threshold percentage from the first rate of change;
halting the flow of the oxidizing agent into the furnace when substantial completion is indicated;
introducing a flow of a reducing agent into the furnace to begin a reduction phase;
calculating a third rate of change of the furnace parameter over a third time period;
calculating a fourth rate of change of the furnace parameter over a fourth time period;
comparing the third rate of change with the fourth rate of change; and
indicating substantial completion of the reduction phase when the fourth rate of change deviates by a predetermined threshold percentage from the third rate of change; and
halting the flow of the reducing agent into the furnace when substantial completion is indicated,
wherein the substantial completion of the oxidation phase is determined when the second rate of change is less positive than the first rate of change for the furnace temperature and when the second rate of change is more positive than the first rate of change for the furnace exhaust oxygen concentration, to indicate depletion of readily oxidizable components in the copper.

2. The method of claim 1 , wherein the at least one furnace parameter further includes a furnace exhaust temperature, the method further comprising:
when the substantial completion of the oxidation phase has been determined, confirming the substantial completion of the oxidation phase when the second rate of change is less positive than the first rate of change for the furnace exhaust temperature.

3. The method of claim 1 , wherein the furnace temperature is measured by an optical pyrometer directed at a metal bath in the furnace.

4. The method of claim 3 , wherein the at least one process parameter further includes a molten bath temperature, the method further comprising:
when the substantial completion of the reduction phase is determined, confirming the substantial completion of the reduction phase when the fourth rate of change is less positive than the third rate of change for the molten bath temperature, to indicate that the exothermic reduction reaction is being overtaken by convention cooling and endothermic fuel cracking.

5. The method of claim 1 ,
wherein the substantial completion of the reduction phase is determined when the fourth rate of change is more positive than the third rate of change.

6. The method of claim 1 ,
wherein the furnace temperature is a molten bath temperature;
wherein the substantial completion of the reduction phase is determined when the fourth rate of change is less positive than the third rate of change for the molten bath temperature, to indicate that the exothermic reduction reaction is being overtaken by convention cooling and endothermic fuel cracking.

7. A method of controlling a melting process of copper in a copper melting furnace, comprising:
introducing a flow of an oxidizing agent into a furnace to begin an oxidation phase;
measuring at least one furnace parameter, wherein the at least one furnace parameter includes a furnace exhaust flammables concentration and one or both of a furnace temperature and a furnace exhaust oxygen concentration;
calculating a first rate of change of the furnace parameter over a first time period;
calculating a second rate of change of the furnace parameter over a second time period at least a portion of which occurs after the first time period;
comparing the first rate of change with the second rate of change;
indicating substantial completion of the oxidation phase when the second rate of change deviates by a predetermined threshold percentage from the first rate of change for the furnace temperature or the furnace exhaust oxygen concentration;
halting the flow of the oxidizing agent into the furnace when substantial completion is indicated;
introducing a flow of a reducing agent into the furnace to begin a reduction phase;
calculating a third rate of change of the furnace parameter over a third time period;
calculating a fourth rate of change of the furnace parameter over a fourth time period;
comparing the third rate of change with the fourth rate of change; and
indicating substantial completion of the reduction phase when the fourth rate of change deviates by a predetermined threshold percentage from the third rate of change for the furnace temperature or the furnace exhaust oxygen concentration; and
halting the flow of the reducing agent into the furnace when substantial completion is indicated,
wherein when the substantial completion of the reduction phase is determined, confirming the substantial completion of the reduction phase when the fourth rate of change is more positive than the third rate of change for the furnace exhaust flammables concentration, to indicate a decrease in consumption of the inputted fuel.

8. A method of controlling a melting process of copper in a copper melting furnace, comprising:
introducing a flow of an oxidizing agent into a furnace to begin an oxidation phase;
measuring at least one furnace parameter, wherein the at least one furnace parameter includes a furnace exhaust infrared intensity and one or both of a furnace temperature and a furnace exhaust oxygen concentration;
calculating a first rate of change of the furnace parameter over a first time period;
calculating a second rate of change of the furnace parameter over a second time period at least a portion of which occurs after the first time period;
comparing the first rate of change with the second rate of change;
indicating substantial completion of the oxidation phase when the second rate of change deviates by a predetermined threshold percentage from the first rate of change for the furnace temperature or the furnace exhaust oxygen concentration;
halting the flow of the oxidizing agent into the furnace when substantial completion is indicated;
introducing a flow of a reducing agent into the furnace to begin a reduction phase;
calculating a third rate of change of the furnace parameter over a third time period;
calculating a fourth rate of change of the furnace parameter over a fourth time period;
comparing the third rate of change with the fourth rate of change; and
indicating substantial completion of the reduction phase when the fourth rate of change deviates by a predetermined threshold percentage from the third rate of change for the furnace temperature or the furnace exhaust oxygen concentration; and
halting the flow of the reducing agent into the furnace when substantial completion is indicated,
wherein when the substantial completion of the reduction phase is determined, confirming the substantial completion of the reduction phase when the fourth rate of change is more positive than the third rate of change for the furnace exhaust infrared intensity, to indicate a decrease in consumption of the inputted fuel.

9. A method of controlling a melting process of copper in a copper melting furnace, comprising:
intro

Assignees

• Air Prod & Chem

Inventors

• Gangoli Shailesh Pradeep
• Hendershot Reed Jacob
• Sane Anup Vasant
• Gallagher Michael J
• Slavejkov Aleksandar Georgi

Classifications

• C22B9/16

  Remelting metals (liquating C22B9/02) · CPC title

• C22B15/003 Primary

  Bath smelting or converting · CPC title

• F27D21/0014

  Devices for monitoring temperature · CPC title

• C22B15/00

  Obtaining copper · CPC title

• C22B15/006

  working up of molten copper, e.g. refining · CPC title