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Major Process Hurdle Overcome at the El Boleo Project
http://www.bajamining.com/news/index.php?mod=cnt&act=cnt&id=...
The El Boleo project, located at Santa Rosalia, Baja California Sur, Mexico, is a sediment hosted deposit of copper-cobalt-zinc, with possible indium,
gallium and germanium credits, in a clayey mineral matrix. The copper-cobalt and zinc values in the ore can be leached using sulphuric acid solutions
in a slurry leach process. While the dissolution of the valuable metals into the leach solution is relatively straightforward, the subsequent
separation of metal containing solution from leached solids has historically been challenging. In order to meet this challenge, Baja commissioned a
program of work at SGS Lakefield Research (Lakefield, Canada) to test the ability to successfully carry out solid-liquid separation and washing of the
barren solids. This work was overseen by Bateman Engineering and involved Poc-ck Industrial (Salt Lake City) and Outokumpu (Toronto) in the testing.
Poc-ck and Outokumpu are specialists in solid-liquid separation technology.
Baja is pleased to advise that the solid-liquid separation tests conducted at SGS Lakefield Research have demonstrated that Boleo ores can be settled
and washed in a conventional CCD circuit utilizing high rate thickeners.
Mike Holmes, Bateman Study Manager for the Boleo Definitive Feasibility Study, stated ?The recent successful testwork on settling of diluted and
flocculated Boleo leach slurries resulted in acceptable high-rate thickener area predictions for the CCD circuit at the proposed daily plant feed rate
of 7500 tonnes solid per day. Underflow densities of 25% solids w/w were achieved which are typical for clays of this nature. Results were
consistent across a range of six composite samples tested. The success of the solid-liquid separation testwork has removed a significant amount of
the technical risk from the flow sheet.?
With the success of the solid-liquid separation testwork, Baja is now moving quickly to a first stage integrated pilot plant at SGS Lakefield in
November 2004. This pilot plant will test each of the unit operations in the Boleo flowsheet in a continuous, integrated system (essentially a
miniature version of the full scale plant system).
The simplified Boleo flow sheet now consists of the following steps: conventional crushing, scrubbing and grinding of run-of-mine ore, a two stage
atmospheric leach, partial neutralisation, solid-liquid separation utilizing high rate thickeners, copper solvent extraction and electrowinning.
After iron precipitation, the copper raffinate is then stripped of the contained cobalt, zinc and residual copper utilizing a proprietary extraction
system developed by Commonwealth Scientific and Industrial Research Organization, Minerals Division (CSIRO). Zinc is stripped from the CSIRO
extractant and is then precipitated as a saleable zinc sulphate. Cobalt is stripped into a highly purified solution and is then electrowon to produce
cathode cobalt.
In summary, Baja has made significant technical progress in validating the Bateman process approach to treatment of Boleo copper-cobalt-zinc ores.
Further pilot plant testwork will continue to build confidence in the process flowsheet selected.
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Boleo Pilot Plant Successful Initiation
http://www.bajamining.com/news/index.php?mod=cnt&act=cnt&id=...
Baja Mining Corp. (the ?Company?) is pleased to announce the successful initiation of the Boleo Pilot Plant currently taking place at SGS Lakefield
Research Ltd (?Lakefield?) in Lakefield, Ontario, Canada. The Company?s Vice President of Metallurgy, David Dreisinger, PhD., has been onsite to
monitor the pilot plant testing and data analysis and reports the following:
The pilot plant started on schedule on Tuesday November 16, 2004 treating a bulk sample of Boleo ore grading 1.9% Cu, 0.087 % Co, 0.58% Zn, 3.5% Mn
and 8% Fe. The pilot plant flowsheet is essentially a miniature version of the expected full scale circuit and comprises:
-Attritioning of the ore with grinding of the oversize;
-Acid oxidation leaching of the ore with sulfuric acid in seawater;
-Acid reduction leaching of the ore with sulfur dioxide and sulfuric acid in seawater;
-Partial neutralization with limestone;
-Counter current decantation (CCD) washing of the leach residue in thickeners (to separate the metal rich aqueous solution from the clayey waste);
-Copper solvent extraction/electrowinning (SX/EW);
-Iron removal by pH adjustment and oxidation;
-Thickening of the iron residue (thickened residue goes to main CCD for washing); and
-Direct Solvent Extraction technology (DSX) for selective recovery of cobalt and zinc (and small amounts of residual copper). DSX technology is the
property of Commonwealth Scientific Industrial Research Organisation (CSIRO), Perth, Australia.
The Boleo process circuit is starting well and is being run to a high standard by Lakefield staff with the support of Bateman Engineering (Feasibility
Study Engineer), Baja Mining Corp., and specialist consultants in solid-liquid separation.
Early results are indicating excellent rates of extraction of copper (Cu), cobalt (Co), and zinc (Zn) at +90% Cu extraction, 80 - 85% Co extraction,
and 70 - 75% Zn extraction.
The slurry being fed into the CCD circuit, for separation of the clayey waste from the mineral rich aqueous solution, is settling as anticipated
through the 6 stages of the CCD.
The CCD overflow, the copper, cobalt, and zinc rich aqueous solution, is being processed by copper solvent extraction and electro-winning (SX/EW).
Copper electro-winning began Thursday, November 18, 2004 with the first copper cathode expected on Monday, November 22, 2004.
The copper depleted solution from solvent extraction (the raffinate) is being treated by neutralization (with limestone) and oxidation to raise the pH
and precipitate iron and other impurities. The neutralized and purified solution is now being processed by the CSIRO (Australia's Commonwealth
Scientific and Industrial Research Organisation) DSX solvent extraction technology for cobalt and zinc recovery. The cobalt and zinc recovery circuit
started on Friday, November 19, 2004.
The Pilot Plant, which is budgeted at CDN$1,500,000, will continue until November 28, 2004. Updates on the success of this process milestone will be
provided by the Company as they become available.
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http://www.bajamining.com/company/about/
The Boleo Project is an advanced polymetallic (copper, cobalt, zinc) project located on tidewater on the east coast of the Baja Peninsula near Santa
Rosalia, Baja Sur, Mexico. Baja Mining Corp. owns a 100% interest in the Boleo Project, free of any underlying royalty interests.
In excess of US$25,000,000 has been spent directly on the property in completing approximately 828 drill holes totaling 68,685 meters, metallurgical
testing, and pre-feasibility studies. A positive pre-feasibility study was completed on the project by Bateman Engineering Pty Limited, of Perth,
Western Australia, in February 2002 (the ?Bateman Study?). The Bateman Study principally focused on a new and simpler metallurgical flow sheet for the
processing of ore from the Boleo Property (as compared to the process proposed in an earlier pre-feasibility by Fluor Daniel Wright).
Baja Mining Corp. is proceeding to a Definitive Feasibility Study on the Boleo Project with an anticipated completion date of September 2005. The key
component of the Feasibility Study will be a continuous pilot plant, anticipated to be conducted in late 2004 or early 2005, to demonstrate the
viability of the simplified flowsheet. As part of such pilot plant, testing will be conducted to determine the potential to extract strategic metals,
gallium, indium and germanium, which previous tests have shown to be present in the ore although more work is required to determine their
recoverability.
The Boleo project is currently envisioned to be an 11,500 tonne per day open cut mine designed to produce 46,500 tonnes per year of LME grade copper
cathode, 3075 tonnes per year of cobalt and 18,000 tonnes per year of zinc. However, it is proposed as part of the Definitive Feasibility Study to
test the potential for underground mining using continuous mining machines. If successful this could access ore with a significantly higher copper
grade than that in the current conceptual open cut resource. Management believes that a detailed mine plan to be prepared as part of the Definitive
Feasibility Study may result in a combination underground mine and smaller open pit operation.
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