TIDMNRRP
RNS Number : 7045T
North River Resources Plc
22 July 2015
North River Resources plc / Ticker: NRRP / Index: AIM / Sector:
Mining
22 July 2015
North River Resources plc ('North River' or 'the Company')
Namib Lead Zinc Mine Bankability Strengthened Significantly
following completion of further Metallurgical Testwork
North River Resources is pleased to announce that, following
supplementary metallurgical testwork, confidence in the planned ore
processing solution for the Namib Lead Zinc Project ('Namib' or
'the Project') in Namibia has been improved significantly.
Highlights
-- A critical milestone as North River moves towards the
construction phase at Namib, focused on developing a 250,000 tonne
per annum operation
-- Ore processing flow sheet defined, which eliminates
variability associated with the previously proposed process and
ensures a robust operating environment for future planned
production
o Main variables in mineralogy and flotation chemistry now
accounted for
o Most effective grind size and metallurgical route now
determined
-- Delivering increased confidence in expected concentrate
grades and recoveries with results from wide ranging ore composites
conducted under simulated plant conditions
o Lead ('Pb') concentrate grade of at 62.2% at 91.1% Pb
recovery, and
o Zinc ('Zn') concentrate grade of 52.4% Zn at 89.2% Zn
recovery
North River CEO James Beams said, "The optimisation work carried
out by independent experts provides the Company with a definitive
and robust processing solution for our stand-out Namib Lead Zinc
Mine in Namibia. The improvement in operational control, that this
process flow sheet provides, will add significant value to our
preparations for Front End Engineering and Design ahead of a
construction decision. I look forward to providing further updates
as we incorporate this plant design into the operating model for
the Namib mine."
Overview of the Metallurgical Testwork Programme
Background
In January 2015, North River appointed ALS Laboratories ('ALS')
to conduct a detailed supplementary testwork programme. ALS was
selected for their relevant experience and knowledge of similar
milling operations. The work was conducted to address the
inconsistent grade recoveries experienced via processing routes
proposed as part of the Definitive Feasibility Study ("DFS") which
referred to a 'lack of agreement' on the performance of different
samples.
The lack of a definitive processing solution in the DFS derives
from the fact that the mineralisation at Namib contains the iron
sulphide mineral, pyrrhotite, which responds to flotation in a
similar manner to the minerals, sphalerite and marmatite which are
the primary zinc ore minerals at Namib. This response can lead to a
build-up of pyrrhotite, and consequently iron, in the zinc cleaner
circuit. While iron is common in lead-zinc deposits, it is normally
present as pyrite, which can be more easily depressed during
flotation than pyrrhotite.
The implications of the presence of pyrrhotite were experienced
first-hand in the previous operation and, as a result, intermediate
products had to be dumped to tailings in order to maintain saleable
concentrate quality, but at the sacrifice of zinc recovery during
processing.
At the time of publication of the DFS, the locked cycle tests
which were underway had not yet been completed. The DFS postulated
that the use of magnetic separation as a means of removing some of
the pyrrhotite from the circuit, but the subsequent results did not
support this proposal as zinc recovery was compromised. Therefore
the focus of the latest work was to produce a robust operating
environment, taking into account the main variables in mineralogy
and flotation chemistry.
Optimisation Work
To properly liberate the generally finer zinc minerals, a
separate zinc regrind circuit is required to optimise the overall
zinc recovery and concentrate grade. Extensive mineralogy was
conducted as a precursor to flotation testwork to determine the
most effective grind size. A primary grind of around 80% passing
100 micron level has been selected and this is also a practically
achievable level within the proposed processing system.
Following this, the fundamental issue in improving the
differential flotation performance was the selection of an optimal
reagent regime. The use of zinc sulphate as a reagent, commonly
used in other lead/zinc operations, was identified as a major
contributor to slowing down the sphalerite recovery rate making
effective separation from the pyrrhotite more difficult.
Consequently, testwork was necessary to eliminate zinc sulphate
from the flowsheet and identify a more selective lead collector.
These newer collectors, replacing the more traditional xanthates
and zinc sulphate, have proved successful in the testwork.
Using the optimised grind and new reagent regime, the Company
has developed a robust processing methodology which can operate
with consistent results with a wide range of mineral composition
and particularly with the variable pyrite and pyrrhotite
content.
This different regime has given reproducible results using
locked cycle tests conducted to complete equilibrium. Overall the
reproducible results, from the five different composites tested,
gave the following results:
-- Lead: 62.2%Pb at 91.1% Pb recovery
-- Zinc: 52.4%Zn at 89.2% Zn recovery (optimum Zinc grades
limited by the zinc mineral Marmatite which has a high iron
content)
These are actual results with the top and bottom values
discarded from compatible locked cycle tests. This has obviating
the previous problem of using batch data when the concentrate grade
and associated recoveries can be mutually unsustainable.
Detailed minor element analyses of the above reported
concentrates show no impurities that could affect the marketing
acceptability.
These results are a significant development, removing any
residual concern over operational variability in the processing
plant and demonstrating robust controls of the final saleable
products. This greatly assists in overall project bankability as
the Company moves forward with its financing plans and, in
particular, its discussions with debt financiers.
About North River Resources: North River Resources (AIM ticker:
NRR) is a multi-asset mining exploration and development company
with projects located in Namibia and Mozambique. The Company's
primary objective is to advance its flagship 'Namib Lead-Zinc Mine'
into production.
**ENDS**
For further information please visit www.northriverresources.com
or contact:
James Beams North River Resources Tel: +44 (0) 20 7025
Plc 7047
Andrew Emmott/ Strand Hanson Limited Tel: +44 (0) 20 7409
Ritchie Balmer 3494
Elisabeth Cowell/ St Brides Partners Tel: +44 (0) 20 7236
Limited 1177
Lottie Brocklehurst
This information is provided by RNS
The company news service from the London Stock Exchange
END
MSCLFFFLDFILFIE
North River (LSE:NRRP)
Gráfica de Acción Histórica
De Dic 2024 a Ene 2025
North River (LSE:NRRP)
Gráfica de Acción Histórica
De Ene 2024 a Ene 2025
