AU713910B2

AU713910B2 - Ilmenite upgrading

Info

Publication number: AU713910B2
Application number: AU67990/96A
Authority: AU
Inventors: Jozef Marie Schaekers
Original assignee: BHP Billiton SA Ltd
Current assignee: BHP Billiton SA Ltd
Priority date: 1995-10-04
Filing date: 1996-10-03
Publication date: 1999-12-16
Anticipated expiration: 2016-10-03
Also published as: AU6799096A

Description

46926 AWT:GEH:KP 0/11 Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE

SPECIFICATION

FOR A STANDARD

PATENT

ORIGINAL

N a m of Ap l c n:.

GEN.) LIIE hUnl-

SEC

Acua Inetr*1 JOE MAIE.CAEER Acvetal ieo: ~13 ILMENITE UPGRADING The following statement is a full description of this invention, including the best method of performing it known to us:

I

Page 2 BACKGROUND OF THE INVENTION This invention relates to the upgrading of ilmenite to produce a product which is acceptable in the market place.

Ilmenite is a heavy mineral of iron and titanium. It is generally recovered from beach sand deposits as a relatively pure mineral. Ilmenite has a number of uses.

A principal use is as a raw material for the production of white titanium dioxide pigment.

Ilmenite is extracted in a relatively pure form from natural deposits. However certain trace elements detract from its use as a source material for pigment production. Trace elements relating to the radioactive elements thorium and uranium, and their radioactive daughter products, are of particular concern and are often present to a greater or lesser degree. These elements are objectionable Sbecause the process used for treating ilmenite involves dissolving the titanium content of the ilmenite, leaving behind a residue which contains the radioactive element present at a much higher level than in the ilmenite.

The disposal of the residue presents a problem particularly when radioactive elements are present in a high concentration.

S.

S.S

3 Many methods have been suggested for removing the radioactive elements before ilmenite is sold but, to the applicant's knowledge, all have cost or technical implications.

SUMMARY OF THE INVENTION The invention provides a process for upgrading granular ilmenite which includes the steps of applying acid to the ilmenite grains, heating the grains to approximately 220°C, washing the grains and recovering and drying washed grains.

1 0 The ilmenite grains may be approximately one hundred microns in size.

The acid may be applied by immersing the grains in an acid solution of appropriate strength.

The strength of the acid solution may be from 5% to 30%, or even more, but a preferred strength is approximately 1 5 The acid may be sulphuric acid.

Excess solution may be allowed to drain from the mineral grains.

a *oe' o.^ During, or after, drying the temperature of the grains may be raised.

As discussed above a suitable temperature is approximately 220°C. At this temperature water is evaporated and the grains are left with a coating of concentrated sulphuric acid.

The temperature of the granular ilmenite may be dropped to approximately The granular material may be immersed in hot water having an acid strength of in the region of The grains are drained from the solution and washed and dried.

1 0 BRIEF DESCRIPTION OF THE DRAWINGS The invention is further described by way of example with reference to the accompanying drawing which illustrates in block diagram form a process for upgrading ilmenite according to one form of the invention.

DESCRIPTION OF PREFERRED EMBODIMENT 1 5 Thorium and uranium are often concentrated on the surface of grains of ilmenite. This is because the ilmenite grains often become oxidised on the surface. In the course of time thorium and uranium absorb onto the surface in the oxidised regions of the grains.

1 ~3 *oelo a ol, oooo*.^ oo eO 1 oo- Page The accompanying flow chart illustrates process steps used for upgrading ilmenite according to one embodiment of the invention.

Ilmenite grains 10, with a size of the order of 100 microns, and having a thorium content of from 75 to 200 parts per million are immersed in a 20% sulphuric acid solution 12. The excess solution is then allowed to drain from the mineral grains which thereafter are dried.

The dried grains are then heated in a stage 14, using any appropriate technique, to a temperature of the order of 220 0 C. At this temperature water is evaporated from the grains which are left with a coating of highly concentrated sulphuric acid. The acid dissolves the oxidised surface of the grains and in particular dissolves thorium and uranium and radioactive elements.

S* The material is subsequently cooled in a step 16, to a temperature of the order of 900C, and then is dropped into hot water 18 having an acid strength of approximately The radioactive elements remain in the solution while the mineral grains retain their original structure and condition. The grains are then drained from the solution and washed and dried. The solution can be treated in Sany appropriate way.

Page 6 The thorium content of the ilmenite mineral treated in the aforementioned manner is reduced to less than 20 parts per million. The ilmenite is suitable for sale to pigment producers or alternatively can be converted to titania slag or synthetic rutile, again for sale to pigment producers.

Claims

2. A process according to Claim 1, wherein the acid is supplied by immersing the grains in an acid solution.
3. A process according to Claim 2, wherein the strength of the acid solution is from 5% to 1 0 4. A process according to Claim 3, wherein the strength of the acid solution is approximately A process according to any one of Claims 1 to 4, wherein the acid is sulphuric acid.
6. A process according to any one of claims 1 or 5, wherein, after heating, the grains are cooled before washing.
7. A process according to Claim 8, wherein the grains are cooled to :about 90 0 C. S d 8. A process according to any one of Claims 1 to 9, wherein the grains d are washed in a dilute acid solution.
9. A process according to Claim 10, wherein the dilute acid solution "has a strength of approximately
10. A process according to Claims 10 or 11, wherein the dilute acid is a dilute sulphuric acid solution.
11. A process according to any one of Claims 1 to 12, wherein the 25 ilmenite grains are approximately 100 microns in size. 8
12. A process for upgrading granular ilmenite substantially as hereinbefore described with reference to the accompanying drawing. Dated this 14th day of October 1999 BILLITON SA LIMITED By their Patent Attorneys COLLISON CO.