VANCOUVER, BRITISH COLUMBIA--(Marketwire - Dec. 17, 2012) - Zincore Metals Inc. (News - Market indicators)(LMA:ZNC) ("Zincore" or the "Company") is pleased to report results of laboratory testing intended to optimize its Waelz kiln metallurgical process to beneficiate the zinc and lead oxide ores at its Yanque deposit which is located on the Company's Accha Zinc Oxide District ("AZOD") project in southern Peru. The Company is currently preparing a Pre-Feasibility Study for the AZOD project and expects to publish that report in the first half of 2013.
The test results indicate the opportunity to reduce the operating and capital expenditures reported in the Company's September 2011 Preliminary Economic Assessment ("PEA")*. Highlights include the following:
- Reduced coal consumption by 35% versus PEA tests to achieve zinc and lead oxide recoveries from Yanque ore of ~89% and ~98% respectively, versus ~93% and ~98% respectively as indicated in the Company's PEA
- Successfully raised melting temperature of Yanque ore versus PEA tests with the addition of 10% dolomite flux to avoid melting
- Achieved above results in 4 hour kiln residence time versus 6 hours for PEA tests
Please see Table 1 below for a summary of results achieved using various kiln temperatures and ratios of coal and dolomite. You may also view a summary report of the test results and methodology as well as summaries of previous test results by clicking here. For information on the Company's previous metallurgical process testing, please see our news releases dated April 20th, August 18th and September 23rd of 2010.
*For further information about Zincore's September 2011 PEA, please click here.
Zincore CEO and President, Jorge Benavides, commented, "These laboratory results are very encouraging. They indicate that we may be able to achieve excellent zinc and lead recoveries from Yanque ore of about 89% and 98% respectively, using as little as 250 kilograms of coal per tonne of ore, versus the 400 kilograms of coal used to obtain the results indicated in our PEA. Given that coal, which is used as a reductant to extract the zinc and lead from the zinc and lead oxide minerals of the ore in the kiln, is the largest operating cost component of our metallurgical process, this would clearly be an important economic enhancement."
Mr. Benavides added, "The test results also indicate we may be able to use a flux such as dolomite to increase the melting temperature of the ores from the Yanque deposit in the kiln. Being able to operate the Waelz kiln at higher temperatures will increase the kinetics of the zinc and lead fuming reaction in the kiln, thus improving kiln throughput and potentially reducing CAPEX."
Test Background and Overview
Zincore's Accha Zinc Oxide District project is comprised of the Company's 100%-owned, 50,000 hectare property package in southern Peru. With NI 43-101 compliant Measured, Indicated and Inferred Mineral Resources at its Accha and Yanque deposits and mineralization identified at nine other AZOD targets, the Company proposes to use the Waelz kiln pyrometallurgical process to beneficiate ores from multiple AZOD locations at a single processing facility.
With this in mind, the Company undertook laboratory and pilot plant metallurgical process testing of ores from both the Accha and Yanque deposits in 2010. The extraction of zinc and lead from the Accha deposit ores through high temperature roasting in a Waelz kiln ("fuming") was proven to be successful. However, it was observed that the ores from the Yanque deposit exhibited the tendency to melt at temperatures exceeding 1050 degrees Centigrade, thus inhibiting the fuming process and the subsequent production of zinc and lead.
To better understand the mechanisms and minerals responsible for the low melting point of the Yanque ore, test work was initiated at the Mintek Laboratories in South Africa in 2010. This work found that the presence of potassium bearing clay mineral was the primary cause of the melting. It was proposed that the addition of a flux, such as dolomite or alumina, to the ore in the kiln may suitably increase the Yanque ore melting point. Initial tests were conducted and the results were encouraging.
With the aim of further testing the parameters of the flux hypothesis, Yanque deposit samples were submitted to the Instytut Metali Nieżelaznych ("IMN") in Gliwice, Poland in early 2012. Based on the findings of the previous Mintek work, IMN tests were conducted in the laboratory to characterise the different phases of the Yanque ore in the Waelz kiln process.
Yanque Ore Samples
The original PEA test work was conducted on a sample known as Yanque l with a zinc content ranging from 5% to 20% and lead content of approximately half the zinc content. The Yanque I oreis representative of the Yanque ore that would be mined in the first five years of the PEA-proposed mine plan. The IMN Phase I test work was conducted on Yanque ll ore with a zinc content of approximately 3.6% and a lead content of approximately 7.3%. The Yanque II ore is representative of the latter years of PEA-proposed mine operation.
Both Yanque I and II samples were analysed and it was determined that both samples were identical in composition with the exception of the zinc and lead content and the relative amount of fluoride and chloride. Further laboratory testing also determined that both samples exhibited the same melting temperature behaviour. It was decided to use the Yanque II ore in the IMN tests in order to demonstrate that even with the different zinc and lead ratios, good recoveries could be achieved. Given that the previously tested Accha ores did not exhibit a melting problem, they were not considered for further testing at this point.
IMN Laboratory Tests
Three different sets of tests were run to test different parameters.
- Bunte-Baum-Reerink Method - To determine softening and melting points
- Thermogravimetric Analysis - To measure heat flow and weight changes as a function of temperature
- Additive Test Work - 13 different laboratory kiln tests to determine the effect of varying temperatures and coal and dolomite ratios
The results confirmed the suitability of dolomite as a flux for the process and identified the softening and melting temperatures of the ore. Thermogravimetric analysis also revealed the different stages in the process as the temperature was increased, leading to the stage where the lead and then the zinc were reduced and released as fume. Laboratory scale tests in a sealed laboratory rotary furnace studied the effect of temperature, dolomite addition and reducing agent (anthracite and bituminous coal) on the recovery of zinc and lead. When considering combinations of these variables, it was determined that the parameters of Test 4, which achieved zinc and lead recoveries of 89% and 98% respectively, provided the best balance of recovery and additive ratios. Accordingly, it was recommended that a temperature of 1100 degrees Centigrade be used in the kiln design with an addition of at least 10% dolomite, or other flux, and a 25% coal (reducing agent) to ore ratio. Under these conditions, residence time in the kiln is expected to be approximately 4 hours. For the 13 tests in total, average recoveries of 85% and 93% for zinc and lead respectively were achieved.
This compares very favourably with 2010 pilot plant testing of the Yanque I ores where initial "parameter" testing (single tests) recoveries of up to 93% for zinc and 98% for lead were achieved using a ratio of 40% anthracitic coal to ore. However, in continuous testing over a 96-hour period, recoveries averaged 78% for zinc and 91% for lead. Melting of the charge within the kiln during continuous testing was found to be the cause for the loss in recovery. Of note, residence time in the kiln under these conditions was 6 hours.
As final points, it was noted that the percentage zinc recoveries from the Yanque II ore were lower than for those from Yanque I ore as lower zinc grades make it difficult to achieve recovery in excess of 90%. It was also noted that the Yanque II test results are consistent in nature with those from the Yanque I and Accha test results, which were performed at other facilities.
TABLE 1 - Summary of Additive Test Results
(a) Bitumous coal used instead of anthracite
(b) Melting of the material observed and test stopped at 3 hours
(c) Melting of the material observed in final stage of test
Next Steps - Pilot Plant Testing
The next phase of the test work has commenced utilising a 100 kg per hour Waelz pilot plant treating two 2 tonne Yanque ore samples at IMN. Tests on flux and the reducing agent consumption will be the focus of the test work, as well as the residence time of the material in the furnace.
All test work was done at the IMN facility in Gliwice, Poland. IMN is well versed in Waelz kiln technology and has laboratory and pilot plant equipment suitable for Waelz kiln design test work.
The laboratory work was operated by staff from IMN under the guidance of Michael Valenta Pr. Eng. (Intl) of Metallicon Process Consulting (Pty) Ltd ("Metallicon") of Hartbeespoort, South Africa. Mr. Valenta has inspected the IMN facility to ensure it meets international best practices and that all issues related to sample preparation and process are of the necessary high standards. Throughout the test program the necessary checks and balances were applied to ensure the robustness of the data. The findings of the test work are such that they supplement the previous test work conducted in both Peru and in South Africa. The IMN analytical laboratory is ISO/IEC 17025 accredited and participates in round-robin sample analysis with third-party facilities.
Metallicon is an independent consulting firm that provides specific, technical expertise in the area of mineral processing. Mr. Valenta is a metallurgical engineer and an internationally registered Professional Engineer under the Washington Accord. He has significant experience in laboratory, pilot testing and full-scale refinery metallurgical practice and processes.
Michael Valenta, Pr. Eng. (Intl), of Metallicon Process Consulting (Pty) Ltd, has prepared or supervised the preparation of the information contained in this news release and is responsible for the technical information it contains. Mr. Valenta is the Qualified Person as defined under National Instrument 43-101 for this news release. He is independent of Zincore within the meaning of National Instrument 43-101
The Accha Zinc Oxide District Project
The Accha Zinc Oxide District project is composed of Zincore's 100%-owned, 50,000 hectare property package in southern Peru. It has access to excellent infrastructure and currently hosts NI 43-101 compliant Measured, Indicated and Inferred Mineral Resources at its Accha and Yanque deposits. Mineralization has also been identified at other District project targets. The Company proposes to use a Walez kiln pyrometallurgical process to benefit ores from multiple AZOD locations at a single processing facility. In addition to the standard studies which make up a Pre-Feasibility report, the Company has been placing particular emphasis on studying ways to improve project operating and capital expenditure economics as well as the commercial terms applicable to final products.
Zincore is a Vancouver-based mineral exploration company focused mainly on zinc and related base metal opportunities in Peru. The Company's common shares trade on both the Toronto and Lima Stock Exchanges under the symbol ZNC. For more information, please see our website at www.zincoremetals.com.
Forward-looking Statements: Statements in this release that are forward-looking, in particular with regards to the potential of the Accha Zinc Oxide District project, are subject to various risks and uncertainties concerning the specific factors disclosed under the heading "Risk Factors" and elsewhere in the Annual Information Form of Zincore dated March 19, 2012 which is filed with Canadian securities regulatory authorities and available on SEDAR (www.sedar.com). Such information contained herein represents management's best judgment as of the date hereof based on information currently available.
The Preliminary Economic Assessment discussed is preliminary in nature, and includes inferred mineral resources that are considered too speculative geologically to have the economic considerations applied to them that would enable them to be categorized as mineral reserves, and there is no certainty that the PEA will be realized. Mineral resources are not mineral reserves as they do not have demonstrated economic viability.