AU622346B2 - Graphite ore attrition - Google Patents

Description

THE COMMISSIONER OF PATENTS.

Edwd, Waters Sons, Melbourne.

COMMONWEALTH OF PATENTS ACT 19 COMPLETE SP

(ORIGINAL)

Application Number: PJ 5720 Lodged: 11th August, 1989.

STR2 3 4 6 52-69

ECIFICATION

Form Class Jn-. Class Complete Specification Lodged: Accepted: Published: Priority Related Art Name of Applicant: INDUSTRIAL MINERALS RESEARCH AND DEVELOPMENT PTY. LTD.

Address of Applicant: Curtin University of Technology, School of Applied Chemistry, Hayman Road, Bentley, W.A. 6102.

Actual Inventor M.E. KEENEY Suite 16, 32 Jubilee Street, South Perth, W.A. 6152.

Address for Service WATERMARK PATENT TRADEMARK ATTORNEYS.

LOCKED BAG NO. 5, HAWTHORN, VICTORIA 3122, AUSTRALIA Complete Specification for the invention entitled: GRAPHITE ORE ATTRITION The following statement is a full description of this invention, including the best method of performing it known to 1.

JL

-2- GRAPHITE ORE ATTRITION This invention relates to the recovery of graphite from ore bodies particularly the preliminary separation of graphite.

Graphite is found in nature as a black lustrous soft mineral and occurs mostly in metamorphic rocks. Due to its softness it marks other substances readily and is greasy to touch. It is virtually infusible, resistant to chemical attack and a good conductor of heat and electricity. These properties make it widely applicable for a number of industrial uses.

Graphite is graded according to its flake size, carbon content and type and amount of impurities. Generally Gt the larger the flake size and higher the carbon content the Geq more valuable the graphite. Normal cr crucible grade graphite must have a carbon content of 85% and be coarser i "o than 150 mesh. Graphite used for pencils, lubricants and I batteries requires a grade of about 94% and for electric S. motor brushes a grade of 98% carbon is required.

Graphite usually occurs in deposits intermixed with a range of gangue materials including clay. Conventionally where the ore is in a hard form physical separation is S preceded by grinding to reduce particle sizes and increase tc the ease of separation. This has also been the case with 4 25 graphite ores. However a measure of quality in refined graphite is flake size and the retention of flake characteristics. Grinding is destructive of flake quality and produces lines that is detrimental in later physical i separation.

It is therefore an object of this invention to achieve breakdown of the ore body with minimal grinding.

ii Fl Cf 4d t ti Ii I t f-t -3- To this end the present invention provides a method of subjecting a graphite ore body to attrition to enable separation of the graphite from the surrounding host gangue material wherein the as mined ore is sprayed with or exposed to an aqueous surfactant solution or dispersion for a period of time sufficient to achieve spalling of the ore.

It has been found that this technique is effective for a majority of ore types although there are some (usually with lower kaolin or clay content) that do not respond to this treatment and conventional grinding has to be used.

Surprisingly, it has been found that with certain host rock the aqueous solution swells the gangue minerals, resulting in spalling liberating the graphite from the host mineral.

The clear advantage derived from-the method of this 15 invention is that flake size of the graphite can be preserved. Subsequent physical separation of the flake from the gangue is enhanced.

Aggregate attritioning work has found that of the ore types tested, approximately 60% of them breakdown readily over a 12-48 hour time period under the action of a commercial grade surfactant at varying concentrations with the remaining 40% showing either slight breakdown or minimal response to the applied conditions.

Settling of fine clays and graphite flake has not 25 presented a problem with most samples settling out in about 1-2 hours after being greatly agitated. A pure graphite sample will settle out in about 0.5 hours showing that the clay and other gangue minerals have only a small effect on the settling of samples.

Any commercially available surfactant can be utilized preferably in concentrations above l0ppm.

Surfactant concentration and temperature and treatment times vary according to the ore body and the degree of spalling required.

t till (I I 4 Ii 11 ii lF 4 After attritioning the treated ore is preferably subjected to a froth flotation to separate the graphite flake from the gangue so that the graphite can be further treated to remove other impurities.

Experimental work carried out in relation to the invention will now be described.

Selected samples were immersed in commercial surfactant solutions of varying concentrations (10ppm 1000ppm). The average sample size used for each test was 150g. Initial tests were carried out at room temperature (approx. 25 0 C) with further tests carried out at higher temperatures (50°C 80°C). Higher temperature tests were carried out under slight agitation with the aid of a Grant shaker-water bath. This type of testing was reserved for ore 15 types which showed resistance to the initial attritioning test procedure.

Results from these initial tests were very encouraging. High concentrations (1000ppm) and ambient conditions (room temerpature, no shaking) proved to be adequate for complete breakdown of approximately sixty percent of the ores tested. Breakdown times were variable between ores but most were fairly rapid in the vicinity of twelve hours. Some ore types broke down within thirty minutes of immersion in the commercial surfactant solution.

Listed below is a table showing ores tested and their respective response to the applied conditions.

Aggregate Attritioning Results

S

S r~ St S

S

*r S (*55 S C CCt Sample Classificatioi Observation

A

I: Weathered Graphite Gneiss, coarse flake (<2mm) Slow breakdown observed with 1000ppm surfactant. Complete attrition after approximately 36 hours under ambient conditions.

Sample Classification:

B

Weathered Graphite Gneiss, coarse flake (<2mm) r Observation Sample Classification:: Observation Sample Classification: Observation ii i *r 4 t 4 Sample Classification: 5 Immediate breakdown at 1000ppm. 12 hours required at 10ppm for complete liberation of graphite under ambient conditions.

C

Weathered Graphite Gneiss, coarse flake Near complete breakdown observed after 24 hours. However some hard aggregates remained. Dosage of 1000ppm under ambient conditions.

D

Weathered Graphite Gneiss, fine flake (<lmm) Complete breakdown of ore after a 12 hour period at a dosage of 10ppm under ambient conditions.

E

Weathered Graphite Gneiss, fine flake (<lmm) Sample taken had liberated most flake graphite after a 36 hour period, however some hard aggregates remained. The dosage was 1000ppm under ambient conditions.

Weathered Graphite Gneiss, amorphous No noticeable breakdown at the most extreme conditions Dosage of 1000ppm, temperature of 80 0 C, and high degree of agitation.

G

Weathered Graphite Gneiss, amorphous Complete breakdown of aggregate observed within a 12 hour period at a dosage of under ambient conditions.

Observation 2 Sample Classification: Observation 30 Sample Classification: Observation -L I ii Y- -7 Sample Classification: Observation 6

H

Weathered Graphite Gneiss, amorphous Near complete breakdown of aggregate only at the most extreme conditions although some hard material did remain after a 24 hour period.

Sample Classificatior Observation SIt Sample Classificatior 15 Observation Sample Classificatior Observation t I

I

i: Weathered Graphite Gneiss, amorphous As with the previous sample, breakdown of the aggregate only occurs under extreme conditions. Ore showed no sign of breakdown under any other experimental conditions.

J

i: Weathered Ferruginous Graphite Gneiss, coarse flake (<2mm) Complete breakdown of the aggregate observed at a dosage of 10ppm under ambient conditions.

SK

i: Weathered Ferruginous Graphite Gneiss, coarse flake (<2mm) :No breakdown of the aggregate observed even under the most extreme conditions.

L

i: Weathered Ferruginous Graphite Gneiss, coarse flake (<2mm) :Approximately 50% breakdown of the aggregate under ambient conditions at a dosage of 1000ppm. Hard sections remained after a 48 hour period.

M

i: Weathered Ferruginous Graphite Gneiss, fine flake (<1mm) ii i t 3'I Sample Classificatior Observation Sample Classificatior 1 01 -1 i I- r Observation Sample Classificatior Observation Sample Classificatior Observation 4 1 S 15

I*

I

Sample Classification Observation Sample Classification Observation 7 Near complete breakdown of aggregate under ambient conditions at a dosage of 1000ppm.

Some relatively hard sections remained after the 48 hour period of test.

N

i: Weathered Ferruginous Graphite Gneiss, amorphous Complete breakdown of aggregate observed under ambient conditions at a dosage of after a 12 hour time period.

0 i: Graphitic Magnesite, fine flake/amorphous Only very slight beneficiation of aggregate sample tested under the most extreme conditions. Hard core of the sample ore remained after a 48 hour time period.

P

Graphitic Magnesite, fine flake/amorphous Near complete breakdown of aggregate under ambient conditions at a dosage of 1000ppm and a time period of 36 hours. Some hard ;ections did remain after this period and appeared to be unaffected by the applied conditions.

Q

Graphite Magnesite, fine flake/amorphous :Negligible breakdown observed under the most extreme conditions over a 48 hour time period.

R

Graphitic Ironstone, coarse flake (<2mm) Approximately 50% breakdown of aggregate observed over a 36 hour tie period at a dosage of 1000ppm.

Sample Classification Observation r U-F.; 1 II_ 111~311~- I~-CC Sample Classification: Observation Sample Classification: Observation Sample Classification: Observation

LI

it i]Y r 15 -8-

S

Graphitic Ironstone, fine flake Moderate breakdown of aggaregate observed under ambient conditions at a dosage of 1000ppm. Hard sections of ore remained after a 36 hour time period.

T

Graphitic Ironstone, fine flake (<1mm) Negligible breakdown of aggregate under the most extreme conditions after a 36 hour time period.

U

Graphitic Ironstone, fine flake (<1mm) No breakdown of aggregate observed under extreme conditions after 36 hours but the sample had softened considerably and may well break down under heap leach conditions.

V

Graphitic Clay, fine flake/amorphous Complete breakdown of aggregate under ambient conditions at a dosage of l0ppm after 12 hrs.

W

Graphitic Clay, fine flake/amorphous Aggregate breakdown under abmient conditions with extreme agitation at a dosage of 1000ppm over a time period of 48 hours.

X

Graphitic Clay, fine flake/amorphous Near complete breakdown of aggregate under ambient conditions after a period of 24 hours at a dosage of 1000ppm. Some hard sections did remain after this period.

Sample Classification: Observation Sample Classification: Observation Sample Classification: Observation 9 It can be concluded from these results that although the material is of the same basic ore type, it does not necessitate that the aggregate will breakdown under the action of the commercial surfactant. It can be seen that the most favourable results have come from the weathered grahite gneiss and weathered ferruginous graphite gneiss which hold the majority of the more valuable coarse flake material, with other ore types showing varied levels of resistance to the applied conditions. X-ray diffraction studies were carried out to find whether there were any dissimilarities in similar ore types that had shown different behaviour under the commerical surfactant solutions.

It can generally be concluded that the coarse flake material of any one particular gneiss readily breaks down under the influence of the commercial surfactant whilst fine to amorphous type graphite acts differently for each particular gneiss which it is aggregated with. The clay type gneiss' tested all broke down under the applied conditions t t whereas the ironstone and magnesitic gneiss' showed variable reactions to the applied surfactant system.

Further testing of larger samples has also been carried out. Various core samples of graphite ore were subjected to a six-month heap-attritioning test. The test was designed to simulate the effect of using a surfactant-solution spray on stock-piled run-of-mine as a method of attritioning the ore.

Results from the long-term tests were consistent with the laboratory tests. Breakdown of the various graphite ores ranged from 20% to 80%. The breakdown can be correlated to the amount of kaolin present with the graphite. The surfactant solution penetrates the graphite/kaolin inter-layered composites causing spalling of the graphite flake and liberation.

'I a i 10 Froth Flotation Separation of Graphite The following separation work established that better quality flake graphite can be recovered using froth flotation in conjunction with the heap attritioning method.

Test work has been carried out on heap attritioned graphite core samples which are representative of the types of ore present across the Munglinup deposit. These include the following ore types shown in Table 1.

Table 1. Ore Types of the Munglinup Deposit ii ii ii

(I

t 6< StS

S(

I a C S Ore Type Weathered ferruginous graphite gneiss a. coarse flake b. fine flake c. amorphous 15 Weathered graphite gneiss a. coarse flake b. fine flake c. amorphous Graphitic clay a. amorphous Graphite magnesite a. amorphous Graphite ironstone a. fine flake b. amorphous Abbreviation 1.(WFGGCF) 2.(WFGGFF) 3.(WFGGA) 4.(WGGCF) 6.(WGGA) 7.(GCA) 8.(GMA) 9.(GIFF) 11 Initial Flotation of Heap Attritioned Ore Rougher concentrates from the attritioned core samples were obtained using the following method: Equipment Used:Denver 'Sub A" flotation cell model D-l Sartorius mass balance 4 Buchner flasks and funnels Aluminium pans Whatman No. 4 filter papers 1,5,10 and 20ml syringes Reagents used: Frothers: MIBC :Teepol, :Teric GN4, GN9, :Pine Oil Collectors:Kerosene(neat) r 15 Depressants:Sodium Silicate 10% sol) S400g samples of attritioned ore were floated at 16% solids (in 2.5L water) at natural pH in a 5L flotation vessel with an agitator speed of 1300rpm. 12ml of Na 2 SiO 3 t solution) was added and the samples were conditioned for minutes. A variety of frothers were added during conditioning along with kerosene as a collector.

The composite slurry was floated for 2 min. to separate the Sgraphite. Three separate floats with reagent additions were conducted. The reagent additions for each of the flotation r 25 tests are summarised in Table 2. Water was added to the flotation vessel after each float to maintain the height of the froth.

LIU---LIII~ i 1- WFGGCF (400g) 12 Table 2. Flotation Conditions Cond'n Rougher Cond'n Rougher 1 2 5 2 5 2 6 6 0.2 0.2 i;-l

I:-

-r;

'B

/i j i I i" r i; i Li I Minutes Na SiO (ml) Kerosene (ml) MIBC (ml) Teepol (ml) WGGCF (400g) Minutes Na SiO (ml) Kerosene (ml) MIBC (ml) WGGFF (400g) 15 Minutes Na SiO (ml) Kerosene (ml) GN9 (ml) GN4 (ml) 20 WFGGFF (400g) Minutes Na SiO (ml) Kerosene (ml) GN4 (ml) 25 Teepol (ml) 0.8 4.0 5 12 0.6 0.5 5 12 0.6 0.2 0.2 5 12 0.6 0.2 0.2 6.0 5 2 0.2 Cond'n Rougher 3 5 2 6 0.2 5 2 0.1 0.1 5 2 0.1 0.1 An analysis of the recovered graphite flake for two samples shows the increase in graphite recovery using the heap attrition froth flotation process.

13

LOI

A1 2 03 Fe 2 0, 3 Si0 2 Ca0 MgO Na 2 0

WFGGCF

Feed Clean Float 30.8 73.7 11 3.7 10 6.2 35 10 1.0 0.52 0.96 0.46 0.2 0.41 Tails 12.6 15.0 12.0 49 2.0 1.4 0.28 Feed 30.9 8.4 6.9 32 0.69 8.4 0.05

WFGGFF

Clean Float Tails 76.7 21.8 1.9 9.2 4.1 3.1 39 2.4 3.2 5.9 9.1 0.07 0.16 i)

U

K

S ii Il, if 45,0' LOI (Loss on ignition) is an indication of the graphite content.

These flotation tests conducted on the heap-attributed graphite samples indicate that both hiyher-grade and coarser flake flotation concentrates are achieved using heap-attritioned feed as compared to the conventional crushed and vat-attritioned feed.

The results from the heap-attrition testwork suggest that this attritioning method is an extremely viable, first-stage process for upgrading graphite ore.

From the above it can be seen that the invention provides a unique approach to attritioning graphite ore without grinding.

Claims (3)

1. Method of treating graphite ore to aid separation of graphite from clay containing gangue wherein the mined ore is contacted with an aqueous surfactant dispersion or solution for a period of time sufficient to achieve spalling of the ore.

2. A method as claimed in claim 1 wherein the surfactant concentration is above 10 ppm and the ore body is kept in contact with the surfactant for at least 30 minutes.

3. A method as claimed in claim 1 or 2 wherein the spalled ore is subsequently subjected to froth flotation separation of the graphite flake. DATED the 9th day of August, 1990. INDUSTRIAL MINERALS RESEARCH DEVELOPMENT PTY. LTD. ji i:! j ji I t Ii, 1* U I~( I 12t WATERMARK, PATENT TRADEMARK ATTORNEYS, 290 BURWOOD ROAD, HAWTHORN, VIC. 3122. AUSTRALIA. DBM:JZ (10s36) j