MOUNT BURGESS MINING N.L. 10 February 2021
ASX CODE: MTB
KIHABE-NXUU POLYMETALLIC Zn/Pb/Ag/Ge/V PROJECT BOTSWANA
ANALYSIS OF MILLED SIZE FRACTIONS - VERTICAL MILLING TEST WORK
VERTICAL MILLING TEST WORK
On 3 December 2020, the Company released an announcement in respect of Vertical Milling test work conducted by Energy and Densification Systems (EDS) South Africa on Nxuu Deposit samples.
EDS has developed a Vertical Milling process which may require as little as 25% of the power required for a conventional Ball/SAG/ROD mill, if able to work effectively on the ore being milled.
Half HQ diamond core from 14 holes drilled into the Nxuu Deposit (Refer to Figures 1 - 6), amounting to 688kg with a maximum size of >50mm and an F80 of 47.68mm was used by EDS for this comminution test work.
TEST WORK RESULTS
The results from this test work were very encouraging, indicating the ability, after primary and secondary crushing to <40mm, to reduce the particle size through the vertical mill to a P80 of 1mm (1,000 microns) for a 2kWh/t power requirement. A further reduction to 106 microns at 80t/h through a small ball mill with an estimated average work index (BWi) of 10kWh/t should only require an additional 6.5kWh/t. The ball mill's efficiency is enhanced by microfractures that occur in the minerals and milled product caused through the EDS Vertical Milling process. This enables them to be broken down more easily than normal in the ball mill.
A typical ball mill feed at a crush size of 12mm would require at least an extra 40% of power, estimated in the region of 10kWh/t. Also, a typical ball mill has a capital cost significantly higher than that of a Vertical Mill.
EDS 10 HORIZONTAL SHAFT VERTICAL MILL
The EDS 10 horizontal shaft Vertical Mill has 180 agitating attachments known as flingers which rotate at speeds of up to 60 m/s. Opposing flingers rotating towards one another create large impact forces on gravity fed material which can be impacted up to 24 times per second before being discharged from the mill. This allows for significant potential to break down particles, creating a high ratio of fines.
The opposing rotating flingers generate what is known as impact force breakage. Impact force breakage breaks down particle sizes in several dimensions. This differs from what is known as compressive force breakage, such as occurs in a ball mill where a particle is mostly broken in two at its weakest point.
CONCENTRATION OF MINERALISATION WITHIN CERTAIN MILLED SIZE FRACTIONS
With certain minerals, such as chromite ores, impact forces are inclined to separate the minerals at their weakest point. The weakest point is inclined to be right at the point where the minerals contact with the host gangue. This weak point separation could therefore generate a concentration of mineralised product within particular size fractions.
ASSAYING MILLED SIZE FRACTIONS
For this reason, after the Vertical Milling test work was completed, EDS took 5,049.6 grams of samples from 12 size fractions of the milled product, ranging from 1,700 microns down to 38 microns, so that it could be assayed to ascertain if any particular size fractions contained excessive concentrations of mineralisation.
Assays were conducted in Australia by Intertek Genalysis for Zn/Pb/Ag/Cu/V/Ge on all size fractions.
ANALYSIS OF THE ASSAY RESULTS OF MILLED SIZE FRACTIONS
Analysis of the assay results from the milled size fractions concluded that in this instance no particular milled size fraction showed excessive concentrations of mineralisation. It is likely that this is the case because the Nxuu Deposit is totally oxidised.
Being totally oxidised it is possible that there is no longer a distinctive weak zone at the contact point between mineralised domains and the host gangue. Such weak zones can occur in sulphide deposits where impact force breakage separation can cause mineralised concentrations within certain particle sizes.
As the Vertical Milling test work has not previously been applied to Nxuu Deposit type mineralisation, it is also possible that none of Zn/Pb/Ag/Cu/V/Ge behave in the same manner as chromite.
CONCLUSION
It was necessary for assaying to be conducted on the various EDS vertically milled size fractions to investigate the possibility of particle size concentrations of mineralisation. The fact that there was not any excessive concentration of mineralisation within any of the size fractions assayed will not have any impact on:
• the planned treatment and extraction processes.
• the fact that the test work has shown that by using the EDS Vertical Mill, there will be a reduction of power required of some 40%, compared to that required when using a conventional Ball/SAG/Rod mill.
FIGURE 1
! 7,821,J
I
0
0
w
0
0
0
�
�
�
0
0
0
0
I
,821,880N
7,S21,760N
7,821,700N
1,s21,GG0N . ,.. - - -■ ----i-----+-----------___•
NXDD048
- --
7,821,640N
DRILL HOLES FROM WHICH CORE WAS SELECTED FOR EDS VERTICAL MILLING TEST WORK
NXDD031
·-s£cnoN 8
-
NXUU DEPOSIT NORTH
AREA
DRILL HOLES FROM WHICH CORE WAS SELECTED FOR VERTICAL MILLING TEST WORK
7,821,750N
7.00m
_-----------3.00-m @· 70.0.403m¾ 10.0Dm
*
GERMANIUM
33.00m
40.00m ··�
=====Z3.00m
25.00m
23.m @ l.47%
8.00m@Gppm ,·
33.00m
� ----------•���Dm 1.00m@298ppm (238ppm}
33m - 4.00m @ 0.46%
--- 37.00m · 7.0Dm
*
NXDD037, 33.00m core submitted to EDS For Vertical Milling Test Work
LEGEND
RECO NC E!QUT GE FOR
blAg
(Recoverable Vanadium Pentoxide)
7,821;B00N
omOw
0
0 xo z.
6.95m. ------------��
*
12.48m 19.43m
*
NXDD043,12.48m core submitted to EDS for Vertical Milling Test Work
c ow
0
X �
0" 0
KALAHARI SAND
15.00m@1,398ppm (1,118ppm)
1.00m@325ppm (260ppm}
KALAHARI SAND 5.1Sm. �======-
.9.055mm @ 186ppm (149ppm) m
7.43m@ l,269ppm (1,0lSppm}
20.95m
2�23.0o0om l.00m@210ppm (168ppm) 2_45.0402m 430.5.080m@305ppm (244ppm)
MINERALISED OXIDISED QUARTZ WACKE
34.00m 1.00m@232ppm (186ppm) DOLOSTONE BASEMENT
41.95m
4o.o3o6m.00.m
31.00m
EOH
7,821,700N
----=-=������] 6.00m
0.3%-1% 1%-3%
3%-4%
5%-0%
•!O�O�l!O:S�T�O:N:E�BAS: EM:E:N�T�4:9.� :64; �m =���.00m ( � •· 3•2· b4m � - - �-OOm 0.64m@1,719ppm {1,375 ppm)
VANADIUM PENTOXIDE
�
MINERALISED OXIDISED QUARTZ WACl<>
FIGURE 2
w o 0 0 ꝏ Xo Z
KALAHARI SAND
34.00m -------------�.o�:.00m 2.00m@295ppm { 236ppm)
* 15.64m
*
{est)
10.00m @
39.00m 4ppm
· � o 402m-�[g39.ꝏm
w �- 3 42.00imo7m
3
49
�:�®
NXDD036,15.64m core submitted to EDS for Vertical Milling Test Work
34 om 34
39.00m.
36.00m 38.00m
·
4 0.93m@889ppm { 71lppm)
1.00m@867ppm (694ppm)
44.O0m .
0.10% 44
50.95m EOH
49.64
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Mount Burgess Mining NL published this content on 10 February 2021 and is solely responsible for the information contained therein. Distributed by Public, unedited and unaltered, on 10 February 2021 01:16:05 UTC.
