TIDMBKY
RNS Number : 0804Y
Berkeley Resources Limited
16 December 2010
16 December 2010
BERKELEY RESOURCES LIMITED
Highly Encouraging Results from Tank Leach and Heap Leach Test
Work at the Salamanca Uranium Project
Berkeley Resources Limited is pleased to announce highly
encouraging results from completion of the Phase 1 Feasibility
Study tank leach metallurgical test workprogramme at the Salamanca
Uranium Project in Spain. Extensive dynamic leach tests have
yielded uranium extraction in excess of 93% in acid batch leach
tests for bulk samples from Palacios and Alameda and in excess of
87% for representative samples from Sageras. Acid leach is a proven
technology and was previously used in the Quercus Processing Plant
at the Salamanca Operation from 1994 to 2000.
Key results from this test work undertaken at the SGS Lakefield
Laboratories in Perth, Australia, are summarised below:
-- Leach recoveries greater than 93% at Palacios and Alameda and
87% at Sageras using an acid based process at high slurry densities
of 1.7 to 1.8;
-- Low power consumption due to a relatively coarse grind in the
leach of P80 750 microns;
-- Rapid leach times - approximately 10 to 12 hours at Alameda
and 12 to 14 hours at Sageras;
-- Ambient leach temperatures of 20 C;
-- Lowsulphuric acid consumptions of 7 to 12 kg/t at Sageras, 15
to 18 kg/t at Alameda and 23 to 25 kg/t at Palacios;
-- Minimal recovery of impurities;
-- A simplified extraction flow sheet, similar to that employed
in uranium acid leach processing elsewhere in the world;
-- Reduction of environmental issues with the generation of a
"dry" leach residue.
The combination of low acid consumption, coarse grind size and
relatively low power costs in Spain continues to drive the process
operating costs to +/- US$15/lb U308 - well within the lower
quartile in operations worldwide. Equally important to note are the
rapid leach times from 10 - 14 hours at Sageras and Alameda, which
have a significant impact on the projected CAPEX, by potentially
reducing tankage and associated civil works, agitators and
power.
Heap leach test work is in its initial stages, however, average
recoveries from four 50 day column leach tests of Sageras samples
were similar to tank leach results, although with slightly higher
acid consumption. Intermittent bottle roll tests on Alameda samples
and progress results for small leach columns of material from
Alameda and Palacios suggest higher recoveries, consistent with the
excellent results obtained from two Retortillo column tests in
2009.
The primary focus of the Phase 1 metallurgical test work
programme is to produce sufficient process and engineering data for
recommissioning of the Quercus Plant at an initial production rate
of 2.1 Mlbs of U3O8 per annum. The ongoing heap leach test work is
examining options for increasing production to over 5 Mlbs of U3O8
per annum, and also enabling more informed comparison of both
processing options.
Enquiries - Managing Director: Ian Stalker Tel: +34 608 221
497
RBC Capital Markets: Martin Eales Tel: +44 20 7029 7881
Introduction
The Salamanca Uranium Project consists of four separate areas
containing a number of metasedimentary hosted uranium deposits
located in the western part of the Salamanca Province in Spain.
These deposits are near surface accumulations of open pittable
uranium within close proximity to the Quercus Uranium Processing
Plant.
During the year over 14,500 kg of representative diamond drill
core was sent to the SGS Lakefield Laboratories in Perth, Australia
for a comprehensive metallurgical test work campaign supervised by
Orway Mineral Consultants (WA) Pty Ltd and Kappes Cassiday. The
material was selected on the basis of lithology, oxidation and
grade from the Sageras Palacios North and Alameda South
deposits.
The Phase 1 metallurgical test work programme was aimed at
optimising process conditions for treating the uranium ore at
Sageras, Alameda and Palacios in a tank leach configuration and
enabling the re-commissioning of the Quercus Processing Plant at a
capacity of 2.1 Mlb (0.95 Kt) of U3O8 per annum. It commenced in
March 2010 and was completed on schedule in October 2010.
The following test work was completed:
-- Preliminary mineralogy on the various ore types and leach
residues;
-- Comminution (crushing & grinding);
-- Preliminary ore sorting;
-- Flotation;
-- Ore upgrade by "Crush-Scrub-Screen" process;
-- Tank leaching;
-- Thickening and filtration;
-- Solvent extraction;
-- Geotechnical and geochemical testing of the leach
residues;
-- Effluent neutralization;
-- Preliminary column leaching.
The test work has identified the flowsheet as being the
optimal.
Tank Leach Test Results
The Phase 1 tank leach test work has delivered uranium
extraction rates in excess of 93% at both Alameda and Palacios and
in excess of 87% at Sageras. All tests to date have employed a
coarse grind to the leach feed of P80750 microns with the aim of
minimizing energy requirements in the comminution circuit without
sacrificing yield.
Typical process conditions are summarised in Table 1.
Material Units Palacios Alameda Sageras
----------------- -------- ---------- ---------- ----------
Recovery % 93 93 87
----------------- -------- ---------- ---------- ----------
Sulphuric acid (kg/t) 23 - 25 15 - 18 7 - 12
----------------- -------- ---------- ---------- ----------
Leach Time (hrs) 8 - 12 10 - 12 12 - 14
----------------- -------- ---------- ---------- ----------
Pyrolusite (kg/t) 1.7 - 2.2 1.4 - 1.8 2.0 - 2.5
----------------- -------- ---------- ---------- ----------
Temperature ( C) 20 20 20
----------------- -------- ---------- ---------- ----------
Slurry Specific 1.7 - 1.8 1.7 - 1.8 1.7 - 1.8
Gravity
--------------------------- ---------- ---------- ----------
Table 1 - Leach Process Conditions for Palacios, Alameda and
Sageras
The relatively coarse ground leach residues are readily filtered
and washed to yield good recoveries of soluble uranium.
Sageras
A total of 26 whole-of-ore batch leach tests have provided the
following conditions:
-- acid consumption - low by industry standards at 7 - 12 kg/t
of ore feed;
-- pyrolusite consumption of 2.0 to 2.5 kg/t;
-- ambient temperature of approximately 20 C;
-- coarse grind of P80 750 microns, and
-- leach slurry density of 65% to 70% solids.
Mineralogical studies indicate that recoveries above 87% for
Sageras may not be cost effective.
Palacios
This deposit is the most amenable to acid leaching with high
extractions of uranium at high slurry pH and shorter residence
times. Higher acid requirements (about double Sageras), are close
to the industry average.
Optimal conditions are:
-- acid consumption = 23 - 25 kg/t;
-- pyrolusite consumption of 1.7 to 2.2 kg/t;
-- ambient temperature of 20 C;
-- coarse grind with P80 750 microns;
-- leach slurry density of 65% to 70% solids, and
-- leach pH of approximately 2.
Acid leach extractions of 93% are readily achievable at
Palacios.
Alameda
The Alameda tests yield similar leach efficiencies to Palacios,
but with significantly lower reagent requirements.
High extractions of 93 to 94% were readily and frequently
achieved.
The optimal conditions for leaching the Alameda composite
are:
-- acid consumption of 15 to18 kg/t - low by industry
averages.
-- pyrolusite consumption of 1.4 to 1.8 kg/t;
-- operating temperature of 20 C;
-- a coarse grind size of P80 750 microns, and
-- leach slurry density of 65% to 70%.
Heap Leach
A substantial programme of intermittent bottle roll leach tests
and column tests is in progress at the SGS Lakefield laboratories
in Perth based on representative drill core samples from the
Alameda, Sageras and Palacios deposits Optimisation programmes for
Alameda and Sageras are still at the early stage of crush size
assessment, but preliminary test results utilising 26 bottle roll
tests for Alameda and 14 for Sageras have confirmed the
following:
-- There is a consistent trend of increasing recovery with
increasing head grade;
-- Uranium recovery appears to be independent of sample depth,
lithology type, or oxidation level;
-- There are no identifiable trends of increasing acid
consumption by head grade, depth, lithology type or oxidation
level;
-- The 10-day intermittent roll bottle tests are a much better
indicator of ultimate column test recovery than simple 5-day
tests.
Column test results to date on Sageras lithology composites
(-12.5mm crush in 100mm diameter by 1.7m tall columns) have been
similar to the excellent results obtained on Retortillo samples in
a programme conducted in 2009. Figure 6 presents the results of 4 x
50 day column tests completed on Sageras composites ranging in
grade from 300 to 950 ppm U3O8. Three of the composites were
reduced material while the 4th composite (SMP-T) was nearer-surface
transition material. Extremely consistent leach results are noted,
with excellent uranium recoveries and exceptionally low acid
consumptions.
Heap leach testwork results to date are notable for their
overall coherence which suggests that the dominant control on
recoveries is uranium mineralogy, textures and grain size. Results
from Sageras and Alameda are consistent with earlier results from
Retortillo using 4m x 100mm diameter columns. They are also
supported by progress results for 12 x 1m and 2 x 2m columns that
are currently investigating the effects of crush size on composite
samples from Sageras, Alameda and Palacios.
The programme of optimisation testing with small and
intermediate size columns on Alameda, Sageras and Palacios
composites, will be followed by a similar programme on Retortillo
composites to assist comparisons of tank leach and heap leach
options. The outcomes from this work will also establish parameters
for the Phase two test work utilizing larger columns.
The information in this report that relates to the metallurgical
test work results is based on information compiled by Mr Grenvil
Dunn, who is a Chemical Engineer and a Member of the South African
Institute of Mining and Metallurgy. Mr Dunn is a Technical
Consultant with Orway Mineral Consultants (WA) Pty Ltd who are
consultants of Berkeley Resources. Mr Dunn has sufficient
experience which is relevant to the style of mineralisation and
type of deposit under consideration and to the activity which he is
undertaking to qualify as a Competent Person as defined in the 2004
Edition of the Australasian Code for Reporting of Exploration
Results, Mineral Resources and Ore Reserves (The JORC Code).
The information in this report that relates to Exploration
Results, Mineral Resources or Ore Reserves is based on information
compiled by Mr. Ross Corben, who is a Member of The Australian
Institute of Mining and Metallurgy and an employee of Berkeley
Resources Limited. Mr. Corben has sufficient experience which is
relevant to the style of mineralisation and type of deposit under
consideration and to the activity which he is undertaking to
qualify as a Competent Person as defined in the 2004 Edition of the
'Australasian Code for Reporting of Exploration Results, Mineral
Resources and Ore Reserves'. Mr. Corben consents to the inclusion
in the report of the matters based on his information in the form
and context in which it appears.
A full version of this announcement including images can be
downloaded from Berkeley's website at
www.berkeleyresources.com.au.
This information is provided by RNS
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