Treatment of Green Pellets Using Microwave Energy

a green pellet and microwave energy technology, applied in the field of green pellets containing iron, can solve the problems of micro-cracking or other physical changes in the ore particles, and achieve the effect of facilitating a more complete oxidation of the magnetite ores and reducing processing time and operating costs

Inactive Publication Date: 2011-03-24
ORE PRO PTY LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0006]Using the method of the present invention, microwave energy is used to provide heating to green pellets containing iron to transform magnetite to hematite in a more controllable manner than by heating the pellets using gas-fired heaters or oil burners. Moreover the heating caused using microwave energy is essentially instantaneous, greatly reducing processing time and operating costs when compared with the use of conventional rotary kilns, shaft furnaces and grate kilns. The present invention is further based on the recognition that ensuring that continuous air flow occurs through the rotary kiln facilitates a more complete oxidation of the magnetite ores.
[0009]The risk of plasma production is reduced when the method further comprises the step of screening the green pellets prior to exposing the green pellets to microwave energy to remove fines. Advantageously, the fines removed during the step of screening may be recycled to form a portion of the magnetite concentrate fed to the pelletizing apparatus.

Problems solved by technology

The structural alteration occurred as the result of differences in thermal expansion of minerals within ore particles, as a consequence of exposure to microwave energy, resulting in regions of high stress / strain within the ore particles and leading to micro-cracking or other physical changes within the ore particles.

Method used

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  • Treatment of Green Pellets Using Microwave Energy
  • Treatment of Green Pellets Using Microwave Energy
  • Treatment of Green Pellets Using Microwave Energy

Examples

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example 1

Batch Testing

[0073]A laboratory sized 1 metre diameter pelletizing disc was used for the production of green pellets. The pelletizing disc was operated at approximately 30 rpm at a disc angle of 45 degrees to the horizontal. Green pellets were produced with varying binder types, namely bentonite and an organic binder produced by Lamberti under the proprietary name Carbocel. The organic binder was preferred as the silica content of the bentonite (29-52%) was considered to be too high as it marginally increases the overall pellet SiO2 content and subsequently reduces iron grade. An additional advantage of using an organic binder is its ability to reduce during the heating a curing process, thereby producing a more porous pellet suitable for DRI or blast furnace applications as well as assisting in oxidation within the microwave process.

[0074]The green pellets were screened for fines removal and sized by hand (>15 mm pellets returned as feed material). Selected pellets were subjected t...

example 2

Continuous Testing

[0091]A rotary kiln was used for continuous testing using a 100 mm internal rotating kiln tube approximately 1.5 metre long with variable speed drive and 6 internal 8 mm×8 mm lifters. The kiln tube was constructed of stainless steel / nickel alloy to withstand the high temperatures (˜1150° C.) with external cladding for heat recovery. The rotary kiln had an adjustable kiln angle with microwave chokes incorporated on both feed and discharge ends to limit microwave radiation. The feed and discharge ends of the kiln were supported and guided using an external bearing arrangement. Microwave power was supplied to the furnace using a 5 kW 2.45 GHz microwave generator with the microwaves being introduced into the kiln via aluminium waveguides (62 mm wide×30 mm high). The waveguides were arranged to allow the option of introducing microwaves into the kiln from either feed or discharge ends or both. The kiln was further fitted with a variable speed vibratory feeder for pellet...

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Abstract

An apparatus for producing iron ore pellets containing hematite is described. The pellets containing magnetite are exposed to microwave energy in a heat treatment furnace under oxidizing conditions to convert magnetite to hematite.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application is a divisional application of U.S. patent application Ser. No. 12 / 372,016, filed Feb. 17, 2009, and titled “Treatment of Green Pellets Using Microwave Energy,” which is a continuation of PCT / AU2007 / 001200, filed Aug. 22, 2007, and titled “The Treatment of Green Pellets Using Microwave Energy,” which claims priority to Australian Application No. AU 2006904659, filed on Aug. 28, 2006, the entire contents of which are hereby incorporated by reference.FIELD OF THE INVENTION[0002]The present invention relates to the treatment of green pellets containing iron using microwave energy to effect the transformation of magnetite to hematite.[0003]The present invention relates particularly, though not exclusively, to the use of microwave energy to heat green pellets containing iron using microwave energy to facilitate subsequent processing of an ore to recover iron.BACKGROUND TO THE INVENTION[0004]World iron ore production consists p...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C22B1/00
CPCC22B1/216C22B1/22C22B9/225C22B1/2413C22B4/00C22B1/2406
Inventor RUNDEL, PAUL FRANK
Owner ORE PRO PTY LTD
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