Process for producing high specific gravity material from low grade iron ore

Claim 2

A PROCESS FOR PREPARING A NON-MAGNETIC IRON OXIDECONTAINING MATERIAL HAVING A SPECIFIC GRAVITY OF A LEAST 4.2 FROM AN IRON ORE HAVING A SPECIFIC GRAVITY OF ABOUT 3.6 TO ABOUT 3.9 WHICH COMPRISES THE STEPS OF: A. CALCINING SAID IRON ORE UNDER OXIDIZING CONDITIONS AT A RESIDENCE TIME SUFFICIENT TO MAINTAIN THE ORE AT BETWEEN ABOUT 1700*F. TO LESS THAN ABOUT 2050*F. FOR AT LEAST 20 MINUTES; B. QUENCHING THE CALCINED ORE; AND C. RECOVERING THE QUENCHED IRON OXIDE-CONTAINING MATERIALS; WHEREIN, THE RECOVERED MATERIAL IS NON-MAGNETIC AND HAS A SPECIFIC GRAVITY OF AT LEAST 4.2.

Claim 3

The process of claim 1 wherein the iron ore has a particle size which will pass through a 1/2 -inch screen and remain on a 1/8 -inch screen.

Claim 4

The process of claim 2 wherein the ore has a particle size which will pass through a 3/8 -inch screen and remain on a 1/8 -inch screen.

Claim 5

The process of claim 1 wherein the calcining step is carried out in a rotary kiln equipped with at least one gas burner with its flame directed so as not to impinge upon the raw ore.

Claim 6

The process of claim 4 wherein said kiln is equipped to provide a forced draft of air during the calcining step.

Claim 7

A process for preparing a non-magnetic iron oxide having a specific gravity of at least 4.2 from a raw iron ore having a specific gravity of less than 3.9 which comprises the steps of: a. crushing the raw ore to a particle size not greater than 1 1/2 inches; b. washing the crushed raw ore; c. calcining said washed ore under oxidizing conditions at residence time sufficient to maintain the ore at between about 1700*F. and less than about 2050*F. for at least 20 minutes; d. quenching the calcined ore; and e. recovering the quenched iron oxide-containing material whereby the recovered material is non-magnetic and has a specific gravity of at least 4.2.

Claim 8

A process for preparing a non-magnetic iron oxide having a specific gravity of at least 4.2 from a raw iron ore having a specific gravity of less than 3.9 which comprises the steps of: a. crushing the raw ore to a particle size not greater than 1 1/2 inches; b. washing the crushed raw ore; c. calcining said washed ore under oxidizing conditions at residence time sufficient to maintain the ore at between about 1700*F. and less than about 2050*F. for at least 20 minutes; d. quenching the calcined ore; and e. recovering the quenched iron oxide-containing material whereby the recovered material is non-magnetic and has a specific gravity of at least 4.2.

Claim 9

The process of claim 6 wherein the washed ore is calcined at from about 1800* F. to about 2000* F.

Claim 10

The process of claim 7 wherein the washed ore is calcined for a time period of from 30 to about 45 minutes.

Claim 11

A process for preparing a non-magnetic iron oxide material having a specific gravity of at least 4.2 from a raw iron ore having a specific gravity of at least 3.45 which comprises the steps of: a. crushing the raw ore to a particle size which will pass through a 3/8 -inch screen and be retained on a 1/8 -inch screen; b. washing the crushed raw ore; c. calcining the washed ore at a temperature of about 1800*F. to about 2000*F. for from about 30 to about 45 minutes in a rotary kiln equipped with a means producing an air draft and with at least one internal burner directed to avoid impingement of the flame on the iron ore during the calcining step; d. quenching the calcined material with water; e. recovering the quenched material from low specific gravity materials by a means whereby the iron oxide-containing material is separated from said low specific gravity material; and f. grinding the recovered iron oxides to a particle size such that 97 percent of the material will pass through a 200 mesh screen.

Claim 12

A process for preparing a non-magnetic iron oxide material having a specific gravity of at least 4.2 from a raw iron ore having a specific gravity of at least 3.45 which comprises the steps of: a. crushing the raw ore to a particle size which will pass through a 3/8 -inch screen and be retained on a 1/8 -inch screen; b. washing the crushed raw ore; c. calcining the washed ore at a temperature of about 1800*F. to about 2000*F. for from about 30 to about 45 minutes in a rotary kiln equipped with a means producing an air draft and with at least one internal burner directed to avoid impingement of the flame on the iron ore during the calcining step; d. quenching the calcined material with water; e. recovering the quenched material from low specific gravity materials by a means whereby the iron oxide-containing material is separated from said low specific gravity material; and f. grinding the recovered iron oxides to a particle size such that 97 percent of the material will pass through a 200 mesh screen.

Claim 13

The process of claim 9 wherein the calcining step is performed at from about 1850* F. to about 1950* F.

Claim 14

The process of claim 9 wherein the raw ore is a limonite ore.

Claim 15

The process of claim 9 wherein the raw ore is a goethite ore.