Mar 08, 2010 06:00 ET
International Tower Hill Announces Key Positive Metallurgical Test Results for Livengood Gold Project, Alaska
Gravity, Flotation and CIL Leaching Metallurgical Testing Indicates Average Recoveries of 85-88% Gold and Strongly Support the Milling Concept
VANCOUVER, BRITISH COLUMBIA--(Marketwire - March 8, 2010) - International Tower Hill Mines Ltd. ("ITH" or "the Company") - (TSX:ITH)(NYSE Amex:THM)(FRANKFURT:IW9) is pleased to announce positive initial metallurgical test results for mill processing of the major types of mineralization at the Money Knob deposit at the Livengood Gold Project, Alaska.
On average, 88% of the gold reported to the concentrates during initial combined gravity and flotation gold recovery tests. Results are highly encouraging for the use of a pre-concentration gold recovery system for the Money Knob mineralization (Table 1). These initial pre-concentration gold recovery results suggest that the economics of a mining operation at Livengood could benefit significantly from the utilization of standard flotation and gravity circuits.
Potentially, both the operating and capital costs for a milling operation could be reduced by decreasing the amount of material required during the intensive treatment for gold extraction. The initial test results indicate that concentration produces an 80% reduction in the material volume requiring further treatment to recover gold. The Company is currently engaged in further testing and optimization of both the concentration process and the extraction of gold from the concentrates.
Initial tests of conventional milling using gravity recovery combined with intensive CIL (Carbon-in-Leach) leaching of gravity recovered gold concentrate and CIL leaching of the tails produced gold recoveries averaging 86% for the major types of mineralization identified in the Money Knob deposit (Table 2).
Jeff Pontius, President and CEO of ITH, states: "These initial results are highly encouraging for ITH as we move the Livengood Project up our value expansion curve. The data provides an opportunity to make a major increase in the economic value of the project through a low cost, pre-concentration milling circuit which would significantly increase gold recovery and provide a game changing direction for the Project and its development path."
The Company intends to utilize the results of this ongoing metallurgical test work in the mill-heap leach based Preliminary Economic Assessment (PEA) of the Livengood Project currently being conducted by SRK Consulting for completion in Q2 2010. A key benefit from use of flotation-gravity pre-concentration is that it would dramatically reduce the volume of material requiring cyanide extraction while increasing the grade of the treated concentrate. This would reduce both reagent costs and capital costs. These results are consistent with the character of the Money Knob mineralization, which has a very high native gold content. The Company has expanded its metallurgical program to fully evaluate and optimize this exciting new development.
Table 1
Initial Flotation-Gravity Metallurgical Results
(Averages of 20 composites from two major mineralization types with varying grade and degrees of oxidation)
Mineralization Type % In-Pit Resource Head Grade (g/t gold) Flotation Recovery Additional Gravity Recovery Total Flotation + Gravity Recoveries Concentrate % of Total Sample
Weight
Volcanics 26% 1.23 69% 21% 90% 21%
Sediments 26% 1.45 60% 24% 84% 18%
Total or Weighted Average 52% 1.34 65% 23% 88% 20%
Table 2
Initial Gravity-CIL Leaching Metallurgical Results
(Averages of 20 composites from five major mineralization types with varying grade and degrees of oxidation)
Mineralization Type % In-Pit Resource Gold Recovery from Gravity Concentrate Total Gold Recovery Con + Tails
Cambrian 11% 97% 92%
Volcanics 26% 98% 90%
Upper Seds 26% 92% 82%
KINT 4% 94% 73%
Lower Sand 11% 95% 83%
Total or Weighted Average 78% 95% 86%
Metallurgical Test Methodology
Metallurgical testing was conducted by Kappes, Cassiday and Associates in Reno, Nevada on 20 representative samples from various mineralization types. Each sample was split from composites weighing 200 kilograms which had been constructed from numerous drill intersections representative of the Money Knob deposit. The composites were selected to represent partially oxidized, trace oxidized and un-oxidized material from higher and lower grade intervals in both sediments and volcanic rocks. Flotation tests were run on material ground to 80% passing 0.075mm material. The tails from the flotation concentration process were then run through a Knelson Gravity Recoverable Gold system to ensure that maximum coarse gold was recovered. Optimization testing will focus on improvement of the recovery percentage, reducing the volume of the concentrate and maximizing recovery from the concentrate.
In a separate study of gravity concentration, CIL leaching tests were run on a gravity concentrate, middlings tail and fine tail developed by a Knelson Gravity Recoverable Gold system on material sized to 80% passing 0.075 mm.
Livengood Project Highlights
•Ongoing drilling at the Project continues to expand the deposit at a rapid rate, and the current estimated resource remains open for further expansion. The latest resource estimate (October 2009) of 296.8 Mt at an average grade of 0.85 g/t gold (8.09 Moz) (Indicated) and 164.2 Mt at an average grade of 0.84 g/t gold (4.4 Moz) (Inferred), both at a 0.5g/t gold cutoff, makes it one of the largest new gold discoveries in North America.
•The recently completed PEA shows that with a USD 850/oz gold price, mining the oxide portion of the deposit using only heap leach processing could yield 5.8M recoverable ounces of gold and an NPV(5%) of USD 440M and an IRR of 14.6% over a 13 year mine life.
•Ongoing metallurgical studies focusing on the potential to mill the Livengood mineralization are underway, and the next PEA will consider a combined Mill and Heap Leach operation. Preliminary metallurgical test results indicate that, on average, 56% of the gold will report to a gravity concentrate and that CIL processing of tails will provide significant additional recovery. Final results of these studies are expected in late Q1 or early Q2 2010.
•The outcropping, shallow dipping, thick, tabular deposit in the November 2009 PEA has a low overall strip ratio of 0.8:1 (waste to ore) in the USD 700 pit. The deposit geometry is favourable for a high production mining operation.
•No major permitting hurdles have been identified to date.
The Company wishes to emphasize that the Livengood project has a very favourable logistical location, being situated 110 road kilometres north of Fairbanks, Alaska along the paved, all weather Elliott Highway, the Trans Alaska Pipeline Corridor, and the proposed Alaska natural gas pipeline route. The terminus of the Alaska State power grid lies approximately 55 kilometres to the south.
Project Background
ITH controls 100% of its 44 square kilometre Livengood land package, which is primarily made up of fee land leased from the Alaska Mental Health Trust and a number of smaller private mineral leases. The Company and its predecessor, AngloGold Ashanti (U.S.A.) Exploration Inc., have been exploring the Livengood area since 2003, with the project's first indicated resource estimate being announced in early 2008. The 2009/10 drilling program is part of a series of drill initiatives which mark the first grid drilling resource definition campaign for the project and is only the initial step in what the Company envisions as a major long-term exploration program to define one of the world's larger new gold deposits.
Geological Overview
The Livengood Deposit is hosted in a thrust-interleaved sequence of Proterozoic to Palaeozoic sedimentary and volcanic rocks. Mineralization is related to a 90 million year old (Fort Knox age) dike swarm that cuts through the thrust stack. Primary ore controls are a combination of favourable lithologies and crosscutting structural zones. In areas distal to the main structural zones, the selective development of disseminated mineralization in favourable host rocks is the main ore control. Within the primary structural corridors all lithologies can be pervasively altered and mineralized. Devonian volcanic rocks and Cretaceous dikes represent the most favourable host lithologies and are pervasively altered and mineralized throughout the deposit. Two dominant structural controls are present: 1) the major shallow south-dipping faults which host dikes and mineralization which are related to dilatant movement on structures of the original fold-thrust architecture during post-thrusting relaxation, and 2) steep NNW trending linear zones which focus the higher-grade mineralization which cuts across all lithologic boundaries. The net result is a broad, flat-lying zone of stratabound mineralization around more vertically continuous, higher grade core zones with a resulting low strip ratio for the overall deposit and higher grade areas that could be amenable for starter pit production.
The surface gold geochemical anomaly at the Livengood Project covers an area 6 kilometres long by 2 kilometres wide, of which an area approximately 3 kilometres by 1.5 kilometres has been explored by drilling to date. Surface exploration is ongoing as new targets are developed to the northeast of the known mineralization.
Qualified Person and Quality Control/Quality Assurance
Jeffrey A. Pontius (CPG 11044), a qualified person as defined by National Instrument 43-101, has supervised the preparation of the scientific and technical information that forms the basis for this news release and has approved the disclosure herein. Mr. Pontius is not independent of ITH, as he is the President and CEO and holds common shares and incentive stock options.
The work program at Livengood was designed and is supervised by Dr. Russell Myers, Vice President, Exploration, and Chris Puchner, Chief Geologist (CPG 07048), of the Company, who are responsible for all aspects of the work, including the quality control/quality assurance program. On-site personnel at the project photograph the core from each individual borehole prior to preparing the split core. Duplicate reverse circulation drill samples are collected with one split sent for analysis. Representative chips are retained for geological logging. On-site personnel at the project log and track all samples prior to sealing and shipping. All sample shipments are sealed and shipped to ALS Chemex in Fairbanks, Alaska for preparation and then on to ALS Chemex in Vancouver, B.C. for assay. ALS Chemex's quality system complies with the requirements for the International Standards ISO 9001:2000 and ISO 17025: 1999. Analytical accuracy and precision are monitored by the analysis of reagent blanks, reference material and replicate samples. Quality control is further assured by the use of international and in-house standards. Finally, representative blind duplicate samples are forwarded to ALS Chemex and an ISO compliant third party laboratory for additional quality control.
About International Tower Hill Mines Ltd.
International Tower Hill Mines Ltd. is a resource exploration company, focused in Alaska and Nevada, which controls a number of exploration projects representing a spectrum of early stage projects to the advanced multimillion ounce gold discovery at Livengood. ITH is committed to building shareholder value through new discoveries while maintaining a majority interest in its key holdings, thereby giving its shareholders the maximum value for their investment.
On behalf of international tower hill mines ltd.
Jeffrey A. Pontius, President and Chief Executive Officer
International Tower Hill Announces Key Positive Metallurgical Test Results for Livengood Gold Project, Alaska
Gravity, Flotation and CIL Leaching Metallurgical Testing Indicates Average Recoveries of 85-88% Gold and Strongly Support the Milling Concept
VANCOUVER, BRITISH COLUMBIA--(Marketwire - March 8, 2010) - International Tower Hill Mines Ltd. ("ITH" or "the Company") - (TSX:ITH)(NYSE Amex:THM)(FRANKFURT:IW9) is pleased to announce positive initial metallurgical test results for mill processing of the major types of mineralization at the Money Knob deposit at the Livengood Gold Project, Alaska.
On average, 88% of the gold reported to the concentrates during initial combined gravity and flotation gold recovery tests. Results are highly encouraging for the use of a pre-concentration gold recovery system for the Money Knob mineralization (Table 1). These initial pre-concentration gold recovery results suggest that the economics of a mining operation at Livengood could benefit significantly from the utilization of standard flotation and gravity circuits.
Potentially, both the operating and capital costs for a milling operation could be reduced by decreasing the amount of material required during the intensive treatment for gold extraction. The initial test results indicate that concentration produces an 80% reduction in the material volume requiring further treatment to recover gold. The Company is currently engaged in further testing and optimization of both the concentration process and the extraction of gold from the concentrates.
Initial tests of conventional milling using gravity recovery combined with intensive CIL (Carbon-in-Leach) leaching of gravity recovered gold concentrate and CIL leaching of the tails produced gold recoveries averaging 86% for the major types of mineralization identified in the Money Knob deposit (Table 2).
Jeff Pontius, President and CEO of ITH, states: "These initial results are highly encouraging for ITH as we move the Livengood Project up our value expansion curve. The data provides an opportunity to make a major increase in the economic value of the project through a low cost, pre-concentration milling circuit which would significantly increase gold recovery and provide a game changing direction for the Project and its development path."
The Company intends to utilize the results of this ongoing metallurgical test work in the mill-heap leach based Preliminary Economic Assessment (PEA) of the Livengood Project currently being conducted by SRK Consulting for completion in Q2 2010. A key benefit from use of flotation-gravity pre-concentration is that it would dramatically reduce the volume of material requiring cyanide extraction while increasing the grade of the treated concentrate. This would reduce both reagent costs and capital costs. These results are consistent with the character of the Money Knob mineralization, which has a very high native gold content. The Company has expanded its metallurgical program to fully evaluate and optimize this exciting new development.
Table 1
Initial Flotation-Gravity Metallurgical Results
(Averages of 20 composites from two major mineralization types with varying grade and degrees of oxidation)
Mineralization Type % In-Pit Resource Head Grade (g/t gold) Flotation Recovery Additional Gravity Recovery Total Flotation + Gravity Recoveries Concentrate % of Total Sample
Weight
Volcanics 26% 1.23 69% 21% 90% 21%
Sediments 26% 1.45 60% 24% 84% 18%
Total or Weighted Average 52% 1.34 65% 23% 88% 20%
Table 2
Initial Gravity-CIL Leaching Metallurgical Results
(Averages of 20 composites from five major mineralization types with varying grade and degrees of oxidation)
Mineralization Type % In-Pit Resource Gold Recovery from Gravity Concentrate Total Gold Recovery Con + Tails
Cambrian 11% 97% 92%
Volcanics 26% 98% 90%
Upper Seds 26% 92% 82%
KINT 4% 94% 73%
Lower Sand 11% 95% 83%
Total or Weighted Average 78% 95% 86%
Metallurgical Test Methodology
Metallurgical testing was conducted by Kappes, Cassiday and Associates in Reno, Nevada on 20 representative samples from various mineralization types. Each sample was split from composites weighing 200 kilograms which had been constructed from numerous drill intersections representative of the Money Knob deposit. The composites were selected to represent partially oxidized, trace oxidized and un-oxidized material from higher and lower grade intervals in both sediments and volcanic rocks. Flotation tests were run on material ground to 80% passing 0.075mm material. The tails from the flotation concentration process were then run through a Knelson Gravity Recoverable Gold system to ensure that maximum coarse gold was recovered. Optimization testing will focus on improvement of the recovery percentage, reducing the volume of the concentrate and maximizing recovery from the concentrate.
In a separate study of gravity concentration, CIL leaching tests were run on a gravity concentrate, middlings tail and fine tail developed by a Knelson Gravity Recoverable Gold system on material sized to 80% passing 0.075 mm.
Livengood Project Highlights
•Ongoing drilling at the Project continues to expand the deposit at a rapid rate, and the current estimated resource remains open for further expansion. The latest resource estimate (October 2009) of 296.8 Mt at an average grade of 0.85 g/t gold (8.09 Moz) (Indicated) and 164.2 Mt at an average grade of 0.84 g/t gold (4.4 Moz) (Inferred), both at a 0.5g/t gold cutoff, makes it one of the largest new gold discoveries in North America.
•The recently completed PEA shows that with a USD 850/oz gold price, mining the oxide portion of the deposit using only heap leach processing could yield 5.8M recoverable ounces of gold and an NPV(5%) of USD 440M and an IRR of 14.6% over a 13 year mine life.
•Ongoing metallurgical studies focusing on the potential to mill the Livengood mineralization are underway, and the next PEA will consider a combined Mill and Heap Leach operation. Preliminary metallurgical test results indicate that, on average, 56% of the gold will report to a gravity concentrate and that CIL processing of tails will provide significant additional recovery. Final results of these studies are expected in late Q1 or early Q2 2010.
•The outcropping, shallow dipping, thick, tabular deposit in the November 2009 PEA has a low overall strip ratio of 0.8:1 (waste to ore) in the USD 700 pit. The deposit geometry is favourable for a high production mining operation.
•No major permitting hurdles have been identified to date.
The Company wishes to emphasize that the Livengood project has a very favourable logistical location, being situated 110 road kilometres north of Fairbanks, Alaska along the paved, all weather Elliott Highway, the Trans Alaska Pipeline Corridor, and the proposed Alaska natural gas pipeline route. The terminus of the Alaska State power grid lies approximately 55 kilometres to the south.
Project Background
ITH controls 100% of its 44 square kilometre Livengood land package, which is primarily made up of fee land leased from the Alaska Mental Health Trust and a number of smaller private mineral leases. The Company and its predecessor, AngloGold Ashanti (U.S.A.) Exploration Inc., have been exploring the Livengood area since 2003, with the project's first indicated resource estimate being announced in early 2008. The 2009/10 drilling program is part of a series of drill initiatives which mark the first grid drilling resource definition campaign for the project and is only the initial step in what the Company envisions as a major long-term exploration program to define one of the world's larger new gold deposits.
Geological Overview
The Livengood Deposit is hosted in a thrust-interleaved sequence of Proterozoic to Palaeozoic sedimentary and volcanic rocks. Mineralization is related to a 90 million year old (Fort Knox age) dike swarm that cuts through the thrust stack. Primary ore controls are a combination of favourable lithologies and crosscutting structural zones. In areas distal to the main structural zones, the selective development of disseminated mineralization in favourable host rocks is the main ore control. Within the primary structural corridors all lithologies can be pervasively altered and mineralized. Devonian volcanic rocks and Cretaceous dikes represent the most favourable host lithologies and are pervasively altered and mineralized throughout the deposit. Two dominant structural controls are present: 1) the major shallow south-dipping faults which host dikes and mineralization which are related to dilatant movement on structures of the original fold-thrust architecture during post-thrusting relaxation, and 2) steep NNW trending linear zones which focus the higher-grade mineralization which cuts across all lithologic boundaries. The net result is a broad, flat-lying zone of stratabound mineralization around more vertically continuous, higher grade core zones with a resulting low strip ratio for the overall deposit and higher grade areas that could be amenable for starter pit production.
The surface gold geochemical anomaly at the Livengood Project covers an area 6 kilometres long by 2 kilometres wide, of which an area approximately 3 kilometres by 1.5 kilometres has been explored by drilling to date. Surface exploration is ongoing as new targets are developed to the northeast of the known mineralization.
Qualified Person and Quality Control/Quality Assurance
Jeffrey A. Pontius (CPG 11044), a qualified person as defined by National Instrument 43-101, has supervised the preparation of the scientific and technical information that forms the basis for this news release and has approved the disclosure herein. Mr. Pontius is not independent of ITH, as he is the President and CEO and holds common shares and incentive stock options.
The work program at Livengood was designed and is supervised by Dr. Russell Myers, Vice President, Exploration, and Chris Puchner, Chief Geologist (CPG 07048), of the Company, who are responsible for all aspects of the work, including the quality control/quality assurance program. On-site personnel at the project photograph the core from each individual borehole prior to preparing the split core. Duplicate reverse circulation drill samples are collected with one split sent for analysis. Representative chips are retained for geological logging. On-site personnel at the project log and track all samples prior to sealing and shipping. All sample shipments are sealed and shipped to ALS Chemex in Fairbanks, Alaska for preparation and then on to ALS Chemex in Vancouver, B.C. for assay. ALS Chemex's quality system complies with the requirements for the International Standards ISO 9001:2000 and ISO 17025: 1999. Analytical accuracy and precision are monitored by the analysis of reagent blanks, reference material and replicate samples. Quality control is further assured by the use of international and in-house standards. Finally, representative blind duplicate samples are forwarded to ALS Chemex and an ISO compliant third party laboratory for additional quality control.
About International Tower Hill Mines Ltd.
International Tower Hill Mines Ltd. is a resource exploration company, focused in Alaska and Nevada, which controls a number of exploration projects representing a spectrum of early stage projects to the advanced multimillion ounce gold discovery at Livengood. ITH is committed to building shareholder value through new discoveries while maintaining a majority interest in its key holdings, thereby giving its shareholders the maximum value for their investment.
On behalf of international tower hill mines ltd.
Jeffrey A. Pontius, President and Chief Executive Officer
