Press Release Highlights:
- Historical records of past testwork, and a 21-year long recent history of gold-silver production at the DeLamar Project, are indicative of the potential for mineralization to be amenable to both heap leaching and conventional milling
- Conventional milling at DeLamar from 1977 to 1998 produced mill recoveries averaging 96.2% gold and 79.5% silver with limited recovery variation between oxide, transitional and unoxidized material
- Heap leaching potential to be tested further: past column leach testwork was conducted on mineralized material from both DeLamar and Florida Mountain Deposits (including oxide, transitional and unoxidized material), showing recoveries of up to 84% gold and 64% silver
- Current metallurgical testwork program is expected to provide key data in support of a Preliminary Economic Assessment to be conducted in H1 2019
Vancouver, British Columbia - Integra Resources Corp. (TSXV:ITR ; OTCQX:IRRZF) (the “Company” or “Integra”) is pleased to announce that it has commenced a comprehensive metallurgical sampling and testwork program on the DeLamar Gold and Silver Project (“DeLamar”, or the “Project”), located in the historic Owyhee County mining district in southwestern Idaho. The metallurgical sampling and testwork program will be conducted by McClelland Laboratories, Inc. in Reno, Nevada, under the supervision of Jack McPartland, Metallurgist/Vice President Operations at McClelland Laboratories, Inc.
“The DeLamar Gold-Silver Project has a long history of mining and processing, producing high-grade and low-grade gold and silver during various periods from the late 1800s and late 1900s. An abundance of metallurgical records recovered on-site clearly demonstrate that the metallurgy of DeLamar is not particularly complex, and that historical gold-silver test recoveries using industry standard leaching techniques were excellent,” stated George Salamis, President and CEO of Integra Resources. “Our mission with this initial round of testwork is to follow-up on past conventional milling and heap leach testwork, and to qualify the extent to which heap leaching can potentially be used as an economically viable means of gold-silver extraction on the Project. Given the large amount of heap leach testwork conducted on the Project by previous operators, with recoveries of up to 84% gold and 64% silver in laboratory column leach tests, we are confident that the results should demonstrate that heap leaching is a potentially viable option for the project.”
“The Project hosts an extensive near surface resource that has the potential for bulk mining. In addition, previous mine operators of the DeLamar and Florida Mountain Deposits left behind significant oxidized, transitional and unoxidized gold-silver resources at surface. Metallurgical testwork on this resource will further de-risk the project and provide processing options for the Company as it continues to grow the existing resource and delineate new targets and deposits around the DeLamar area,” noted George Salamis, President and CEO.
HISTORY OF GOLD-SILVER MILLING AND METALLURGY AT THE DELAMAR PROJECT1
Recent Historical Gold and Silver Operational Processing and Recoveries
Records from recent historical gold (“Au”) and silver (“Ag”) processing at DeLamar, as defined by the mineral processing that took place on site from 1977 until 1998, hosts much of the most relevant metallurgical data available to Integra at this time. Processing was performed by crushing, grinding, and tank leaching with cyanide, followed by precipitation with zinc dust and in-house smelting of the precipitate to produce silver-gold doré. Records show that from 1977 through 1992, the mill processed 11.686 million tonnes of mineralized material with average head grades of 1.17 g Au/tonne and 87.1 g Ag/tonne. During this 15-year period, the DeLamar mill recovered, on average, 96.2% of the contained gold and 79.5% of the contained silver. The historical mill feed during this period included oxidized, partly oxidized, and unoxidized materials.
Historical Column Leach Test Work Designed to Evaluate Potential Heap Leaching Options
In the 1980s, the NERCO Mineral Company (“NERCO”) conducted numerous column leach tests using mineralized material from the Florida Mountain Deposit (“Florida Mountain”). The results of this testwork, summarized below in Table 1, demonstrate the potential for heap leach processing of mineralized material at Florida Mountain, and may indicate the amenability of heap leaching on mineralized material from DeLamar as well, based on the similar host-rock types and styles of mineralization for both Deposits. Clarification surrounding the different metallurgical characteristics of Florida Mountain mineralized material versus DeLamar mineralized material is one focus of the current testwork.
Table 1. Compiled NERCO Florida Mountain Column Leach Test Results
(From Statter, 1989, and Hampton, 1988, compiled by Integra, 2017)
|Florida Mountain Area||Crush Size||Calculated Head Grade||Duration||Metal Extraction|
|Inches||Ag g/t||Au g/t||Days||Ag %||Au %|
|Stone Cabin LG||-1||7.71||0.31||60||45.2||85.1|
|Stone Cabin LG||-1/2||10.87||0.34||60||43.1||84.5|
|Stone Cabin HG||-1||15.60||1.61||60||39.3||78.1|
|Stone Cabin HG||-1/2||14.40||1.47||60||47.6||84.3|
|Stone Cabin Dump||1||60.38||3.70||60||39.7*||83.1*|
|Stone Cabin Dump||-1||17.62||0.65||60||31.5*||92.2*|
|Stone Cabin Core||-1/2||15.98||0.62||60||42.9*||92.6*|
|Stone Cabin Core||-1/2||18.17||12.00||60||36.2*||78.0*|
|Tip Top Trench||-2||17.35||1.03||56||41.6*||92.2*|
|Tip Top Trench||-1||19.75||1.10||56||42.8*||91.5*|
|Tip Top Trench||70% -1/4||21.81||1.03||56||45.0*||95.0*|
- *denotes an internal DeLamar mine assay factor was applied to silver and gold analyses
- Sullivan Core refers to drill core from the Sullivan claim in the Florida Mountain Deposit, not the Sullivan Gulch area of the DeLamar Deposit
- Integra is unaware of the column diameter(s) or the oxidation state(s) of the material tested
Statter (1989) reported a pilot column leach test was performed in 1988 using 14,850 pounds of Stone Cabin “run of dump” material. The test was likely conducted at the DeLamar mine laboratory. Leaching was conducted for 63 days resulting in 15.8% silver recovery and 72.2% gold recovery.
In 1987, NERCO initiated construction of a small scale, trial cyanide heap leach pad which was in operation for the last quarter of 1987 until the final quarter of 1990. The trial leach pad used low-grade run-of-mine material that was driven onto the pad by haul truck then ripped by bulldozer to provide permeability. The material size was reported to be approximately 70% at >20 centimeters (>8 inch). The trial pad and stacked material became physically unstable and began to slide downhill towards the tailings facility in 1990. In early 1991, the entire heap was removed and placed into the tailings facility. The trial leach pad was shut down due to physical instability, not due to the lower leach results being obtained during the trial. The Company has surmised that that the stacked material may not have reached the optimum duration under leach, and therefore the overall calculated recovery of only 41% gold and 8% silver may be understated by an unknown quantity.
- NI 43-101 Technical Report and Estimated Gold - Silver Resources, DeLamar Project, Integra Resources Corp. Effective Date March 8, 2018.
2018 Metallurgical Testwork Program on DeLamar and Florida Mountain
The current metallurgical testwork program will address three main objectives, in support of a planned 2019 PEA:
- To establish the milling characteristics of mineralization from the DeLamar and Florida Mountain Deposits;
- To establish the amenability of different mineralization types from both Deposits to potential heap leaching; and,
- To provide the Company with information to establish future “trade-off” parameters of using one or both of the above means of gold-silver extraction on the project.
The program, to be conducted over the next several months at McClelland Laboratories, Inc. in Reno, Nevada, under the super vision of Jack McPartland, Metallurgist/Vice President of Operations at McClelland Laboratories, Inc., will focus on the following:
- Ore Variability (Bottle Roll) Composite Testing
- Column Test Composite Testing
- Load/Permeability Testing
- Scoping Mill Testing, including Bond Ball Mill Work Index tests, cyanidation tests, flotation tests and gravity concentration tests
Sample media used in this metallurgical study has been collected from diamond core drill holes completed over the course of the 2018 drill program at DeLamar and Florida Mountain. Results from the metallurgical sampling program are expected in Q4 2018 and Q1 2019.
DeLamar Exploration Ongoing
Currently two drill rigs are in operation at the DeLamar Project, with 60 drill holes completed over 18,500 m. Many drill assays remain outstanding and are expected to be available for reporting upon in the coming weeks and months.
The scientific and technical information contained in this news release has been reviewed and approved by E. Max Baker PhD. (FAusIMM), Integra’s Vice President Exploration, of Reno, Nevada, and is a “qualified person” (“QP”) as defined in National Instrument 43- 101 - Standards of Disclosure for Mineral Projects.
About Integra Resources
Integra Resources Corp. is a development-stage company engaged in the acquisition, exploration and development of mineral properties in the Americas. The primary focus of the Company is advancement of it’s DeLamar Project, consisting of the neighbouring DeLamar and Florida Mountain Gold and Silver Deposits in the heart of the historic Owyhee County mining district in south western Idaho. The first exploration program in over 25 years is currently underway on the DeLamar Project with more than 20,000 meters planned for 2018. The management team comprises the former executive team from Integra Gold Corp.
ON BEHALF OF THE BOARD OF DIRECTORS
President, CEO, and Director
This news release contains “forward-looking information” and “forward-looking statements” (collectively, “forward-looking statements”) within the meaning of the applicable Canadian securities legislation. All statements, other than statements of historical fact, are forward-looking statements and are based on expectations, estimates and projections as at the date of this news release. Any statement that involves discussions with respect to predictions, expectations, beliefs, plans, projections, objectives, assumptions, future events or performance (often but not always using phrases such as “expects”, or “does not expect”, “is expected”, “anticipates” or “does not anticipate”, “plans”, “budget”, “scheduled”, “forecasts”, “estimates”, “believes” or “intends” or variations of such words and phrases or stating that certain actions, events or results “may” or “could”, “would”, “might” or “will” be taken to occur or be achieved) are not statements of historical fact and may be forward-looking statements. In this news release, forward-looking statements relate, among other things, to: statements about the estimation of mineral resources; magnitude or quality of mineral deposits; anticipated advancement of mineral properties or programs; future operations; future exploration prospects; the completion and timing of mineral resource estimates; the length of the current market cycle and requirements for an issuer to survive in the current market cycle; future growth potential of Integra; and future development plans.
These forward-looking statements are based on reasonable assumptions and estimates of management of Integra at the time such statements were made. Actual future results may differ materially as forward-looking statements involve known and unknown risks, uncertainties and other factors which may cause the actual results, performance or achievements of Integra to materially differ from any future results, performance or achievements expressed or implied by such forward-looking statements. Such factors, among other things, include: possible variations in mineralization, grade or recovery rates; actual results of current exploration activities; actual results of reclamation activities; conclusions of future economic evaluations; business integration risks; fluctuations in general macroeconomic conditions; fluctuations in securities markets; fluctuations in spot and forward prices of gold, silver, base metals or certain other commodities; fluctuations in currency markets (such as the Canadian dollar to United States dollar exchange rate); change in national and local government, legislation, taxation, controls, regulations and political or economic developments; risks and hazards associated with the business of mineral exploration, development and mining (including environmental hazards, industrial accidents, unusual or unexpected formations pressures, cave-ins and flooding); inability to obtain adequate insurance to cover risks and hazards; the presence of laws and regulations that may impose restrictions on mining; employee relations; relationships with and claims by local communities and indigenous populations; availability of increasing costs associated with mining inputs and labour; the speculative nature of mineral exploration and development (including the risks of obtaining necessary licenses, permits and approvals from government authorities); and title to properties. Although the forward-looking statements contained in this news release are based upon what management of Integra believes, or believed at the time, to be reasonable assumptions, Integra cannot assure its shareholders that actual results will be consistent with such forward-looking statements, as there may be other factors that cause results not to be as anticipated, estimated or intended.
Readers should not place undue reliance on the forward-looking statements and information contained in this news release. Except as required by law, Integra assumes no obligation to update the forward-looking statements of beliefs, opinions, projections, or other factors, should they change, except as required by law.