Wrap Text
Prieska Zinc-Copper Project Advanced-Stage Metallurgical Tests Achieve Impressive Recoveries to Saleable Product
Orion Minerals Limited
Incorporated in the Commonwealth of Australia
Australian Company Number 098 939 274
ASX share code: ORN
JSE share code: ORN
ISIN: AU000000ORN1
PRIESKA ZINC-COPPER PROJECT ADVANCED-STAGE METALLURGICAL TESTS ACHIEVE
IMPRESSIVE RECOVERIES TO SALEABLE PRODUCT
- Advanced-stage metallurgical testing of Prieska Project Deep Sulphide material achieves up to 94%
zinc and 86% copper recoveries into marketable concentrates.
- Results were achieved with locked-cycle metallurgical tests designed to simulate plant operations with
the use of modern reagents.
- Results demonstrate metallurgical continuity of deep sulphide deposit and achieved parity with
historical plant performance.
Orion Minerals Ltd (ASX/JSE: ORN) (Orion) is pleased to announce that significant progress has been made
in the metallurgical test work program being undertaken as part of the Prieska Zinc-Copper Project (Prieska
Project) bankable feasibility study (BFS).
“Figures" referred to throughout this announcement can be viewed on the pdf version of the announcement,
available on the Company's website, www.orionminerals.com.au.
The first batch of advanced-stage, laboratory-scale, locked-cycle flotation tests, assessing the efficiency of the
proposed mineral processing route, have achieved up to 94% zinc and 86% copper recoveries into marketable
concentrates, (refer Table 1). The tests are being conducted on the Hypogene Zone (Deep Sulphide Zone) of
the deposit. The Deep Sulphide Zone makes up approximately 95% of the delineated Prieska Project Mineral
Resources by weight (refer ASX release 9 April 2018) and is being targeted for extraction by underground
mining methods.
The latest metallurgical results compare extremely well to the historical performance achieved in past mining
operations when Anglovaal processed the up dip section of the deposit over its 20-year operating history.
Anglovaal achieved over 85% average metal recoveries for both zinc and copper into differentiated, high-
quality concentrates (refer ASX release 15 November 2017).
Locked-cycle testing, which simulates the build-up in concentration of various reagents and other elements
during continuous operation, was conducted on a composite sample representing a blended feed comprising
of 50% material from the north-western area of the deposit and 50% material from the south-eastern area.
The sample tested was composited from recent drill core samples collected from mineralised intersections of
the Deep Sulphide Zone. Further variability tests are in progress to confirm the metallurgical response of the
full extent of the Prieska Deposit and to finally determine the recoveries and concentrate qualities to be targeted
for optimised returns in the ongoing BFS.
When graphically superimposed over the historical plant performance dataset, (refer to Figures 1 and 2 below),
the latest locked-cycle tests, (highlighted in red squares in Figures 1 and 2), compare favourably with the
historical operational performance. The copper recovery results align with the historical trend line, while the
zinc recoveries are above the historical performance. This is an excellent achievement confirming Orion’s
confidence in the project.
Figure 1: Graph showing the copper recoveries into marketable concentrates achieved for various head
grades during historical mining operations (‘Historical Operational Data’)1,2, during 1970 Anglovaal pilot plant
testing (‘Pilot Plant (1970)’) and during the latest locked-cycle testing (“FS Blend #1).
1
Averaged Monthly Production Data (January 1975 – December 1976), Brian Broekman 1991, The Prieska experience: Flotation
developments in copper-zinc separation, J.S. Afr. Inst. Min. Metal., vol. 91, no. 8. Aug. 1991. pp. 257-265.
2
S.K De Kok 1972, Differential Flotation of Copper-Zinc at Prieska Copper Mines (Pty) Limited: A Pre-Liminary Report, Journal of the
South African Institute of Mining and Metallurgy July 1972. pp. 305 – 321.
Figure 2: Graph showing the zinc recoveries into marketable concentrates achieved for various head grades
during historical mining operations (‘Historical Operational Data’) 1,3, during 1970 Anglovaal pilot plant testing
(‘Pilot Plant (1970)’) and during the latest locked-cycle testing (“FS Blend #1).
Table 1: Summary of locked-cycle metallurgical test results for the Deep Sulphide composite sample.
Laboratory-scale, Locked-Cycle Tests
Earlier metallurgical test work resulted in Orion developing a mineral processing flowsheet to treat all the
mineralised zones of the remaining Prieska Deposit using froth flotation and succeeded in producing
differentiated zinc and copper concentrates (refer ASX release 1 March 2018). The final processing flowsheet
developed will incorporate improvements on the mineral processing technology and reagents to those
available to historical operations and will form the basis of process design, equipment selection, equipment
sizing once tested for its effectiveness in continuous operation and its applicability to the various geographic
regions of the defined deposit.
Locked-cycle testing involves the preparation of samples that are representative composites from sub samples
taken from different zones of the deposit and running each composite sample through a laboratory-scale setup
of the flowsheet in open circuit. The products of the open circuit test are recycled five times through the same
flowsheet setup to simulate the build-up in concentration of various reagents and other elements expected
under continuous froth flotation operating conditions. The addition of further repetitive cycles or reagent
addition may yet further optimise total recoveries or achieve higher concentrate grades.
Laboratory-scale, locked-cycle metallurgical variability testing on three additional variability composites is now
being conducted as part of the advanced stages of the metallurgical testing program. This phase of testing
investigates expected performance for a stable reagent suite with the inclusion of recycled scalping and
cleaning streams and the performance of the flowsheet for samples obtained from the different geographic
locations of the deposit.
Locked-cycle test work results
Locked-cycle testing was conducted on a Deep Sulphide zone composite sample representing a blended feed
comprising 50% material from the north-western extent of the Prieska Deposit and 50% material from the
south-eastern extent. This testing resulted in the total recovery of 80% to 86% copper and 91% to 94% zinc
into marketable concentrates. Copper concentrate grades ranged from 21% to 24%, whilst the zinc concentrate
grades ranged from 45% to 54%. Current indications are that zinc recoveries are unlikely to benefit further
from additional cycles, while copper recoveries and qualities have further opportunity for optimisation. The
amenability of the mineralisation to produce flotation concentrates of varying grades will allow mine-to-market
product optimisation to be done at the design and planning stages of the Prieska Project BFS.
Right-sizing planned throughput
Historical mining operations at the Prieska Project treated 3 million tonnes a year of run-of-mine ore. Some of
the mine infrastructure used to support such throughput remains on the project site such as the Hutchings
Shaft barrel that was used as the main hoisting shaft, access roads, power supply line and water supply
pipeline. With the recent upgrade to the global Mineral Resources to 29.4 million tonnes of Mineral Resources
(refer ASX release 9 April 2018), mining studies are now being advanced, as part of the BFS, to right-size the
planned mining operations taking into account how best to fully exploit the defined Mineral Resources and
maximise the use of existing infrastructure.
The investigations into right sizing the mine require that higher throughput mining scenarios be considered, as
well as ensuring that a significant portion of the defined Mineral Resources are upgraded to Mineral Resources
categories that allow them to support a BFS. Infill drilling of the southern extent of the Prieska Deposit has
commenced with fourteen rigs now mobilised, in line with the intention to incorporate as much as possible of
the defined Mineral Resources into the mine schedule of the BFS. The implications of including more of the
Prieska Deposit within the mining studies is that the resource definition drilling will extend into Q4 2018 and
the BFS completion is now scheduled for late 2018 or early 2019. This timing coincides with the scheduled
time for the issuance of the Mining Right in Q2 2019, which is the required statutory authorisation required
before construction, de-watering and mining operations can commence.
3
Averaged Annual Production Data 1973 – 1991 extracted from: Technical Report on the Copperton Project of Repli Trading No. 27
(Pty) LTD, March 2014.
Orion’s Managing Director and CEO, Errol Smart, commented:
"The locked-cycle metallurgical tests are an important step for Orion to demonstrate minimum design metal
recoveries, qualities and concentrate masses to be incorporated in feasibility study work. We are now able to
start trade-off assessments in capital and operating costs for optimised returns.”
Errol Smart
Managing Director and CEO
12 June 2018
Investors JSE Sponsor
Errol Smart – Managing Director & CEO Rick Irving
Denis Waddell – Chairman Merchantec Capital
T: +61 (0) 3 8080 7170 T: +27 (0) 11 325 6363
E: info@orionminerals.com.au E: rick@merchantec.co.za
Media
Michael Vaughan Barnaby Hayward
Fivemark Partners, Australia Tavistock, UK
T: +61 (0) 422 602 720 T: +44 (0) 207 920 3150
E: michael.vaughan@fivemark.com.au E: orion@tavistock.co.uk
Suite 617, 530 Little Collins Street
Melbourne, VIC, 3000
Competent Persons Statement
The information as presented in this report that relates to the results of metallurgical test work at the Prieska
Project is not in contravention of the 2012 Edition of the Australasian Code for Reporting of Exploration Results,
Mineral Resources and Ore Reserves (JORC Code) and has been compiled and assessed under the
supervision of Mr Errol Smart, Orion’s Managing Director. Mr Smart (PrSciNat) is registered with the South
African Council for Natural Scientific Professionals, a Recognised Overseas Professional Organisation
(ROPO) for JORC purposes and has sufficient experience that is relevant to the style of mineralisation and
type of deposit under consideration and to the activity being undertaken to qualify as a Competent Person as
defined in the 2012 Edition of the JORC Code. Mr Smart consents to the inclusion in this announcement of the
matters based on his information in the form and context in which it appears.
Disclaimer
This release may include forward-looking statements. Such forward-looking statements may include, among other things,
statements regarding targets, estimates and assumptions in respect of metal production and prices, operating costs and
results, capital expenditures, mineral reserves and mineral resources and anticipated grades and recovery rates, and are
or may be based on assumptions and estimates related to future technical, economic, market, political, social and other
conditions. These forward-looking statements are based on management’s expectations and beliefs concerning future
events. Forward-looking statements inherently involve subjective judgement and analysis and are necessarily subject to
risks, uncertainties and other factors, many of which are outside the control of Orion. Actual results and developments may
vary materially from those expressed in this release. Given these uncertainties, readers are cautioned not to place undue
reliance on such forward-looking statements. Orion makes no undertaking to subsequently update or revise the forward-
looking statements made in this release to reflect events or circumstances after the date of this release. All information in
respect of Exploration Results and other technical information should be read in conjunction with Competent Person
Statements in this release. To the maximum extent permitted by law, Orion and any of its related bodies corporate and
affiliates and their officers, employees, agents, associates and advisers:
- disclaim any obligations or undertaking to release any updates or revisions to the information to reflect any change
in expectations or assumptions;
- do not make any representation or warranty, express or implied, as to the accuracy, reliability or completeness of the
information in this release, or likelihood of fulfilment of any forward-looking statement or any event or results
expressed or implied in any forward-looking statement; and
- disclaim all responsibility and liability for these forward-looking statements (including, without limitation, liability for
negligence).
Appendix 1: Test Work Methodology
Laboratory-scale flotation tests were conducted on a 1kg batch samples. The samples were milled using a
laboratory rod mill at 50% solids by mass to achieve a target grind of 70-80% passing 75 microns.
The milled slurry was then transferred into a 2.5 litre flotation cell, which was agitated using a Denver D12
flotation machine at an impellor speed of 1200 rpm. Depending on the feed mass, cleaner flotation testing was
conducted in either a 1 litre or 2 litre flotation cell which was agitated using a Denver D12 flotation machine at
an impellor speed of 1000 -1200 rpm. Concentrates were collected by scraping off the froth at 15 second
intervals. A sample of the test product was pulverised and assayed for copper, lead, zinc, iron and sulphur
using the Inductively Coupled Plasma (ICP) analysis method.
Locked-cycle testing involves repetitive batch flotation testing, whereby the flotation test is repeated five times
using recycled intermediate flotation streams. A product sample is collected at the end of each cycle for ICP
analysis.
The total copper circuit recoveries as presented in Table 1, reflect the total recovery to the copper re-cleaner
concentrate and scavenger cleaner concentrate streams in locked-cycle testing. The total zinc circuit
recoveries as presented in Table 1, reflect the total recovery to the high grade cleaner concentrate and low
grade re-cleaner concentrate in locked-cycle testing.
Date: 12/06/2018 08:21:00 Produced by the JSE SENS Department. The SENS service is an information dissemination service administered by the JSE Limited ('JSE').
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