Sudbury, Ontario--(Newsfile Corp. - May 1, 2020) - Rockcliff Metals Corporation (CSE: RCLF) (FSE: RO0) WKN: A2H60G) ("Rockcliff" or the "Company") is pleased to announce the results from ore sorting test work indicating high potential for the use of ore sorting to preconcentrate mineralized material from the 100% owned Tower and Rail deposits located in the Flin Flon-Snow Lake region of Manitoba. Ore sorting is a technology that can select rock with mineralization and separate them from rocks without mineralization, thus upgrading the mineral content of the ore delivered to the mill.
Alistair Ross, President and CEO commented, "The ore sorting characterization test work on our Tower and Rail deposits provides exciting upside for our projects on a number of fronts. With an upgrade ratio of at least 1.4 on both Tower and Rail, ore sorting has demonstrated an ability to reject low sulphide waste. The advantages we see include the following:
- Both ores responded similarly to ore sorting and flotation test work, supporting the hub and spoke strategy for utilizing the same mill and sharing capital between succesive mines;
- Mining dilution, a serious issue for narrow vein mines, is now a manageable cost by using low cost ore sorting and a low cost-in-mine haulage system, such as Rail-Veyor, that Rockcliff is actively investigating;
- Transport costs from the mine sites to the mill will be substantially decreased by keeping the waste rock at site for backfill purposes;
- Milling costs will be substantially reduced by eliminating the waste rock from the mill stream; and
- Tailings impoundment volumes will be substantially reduced by placing the waste in the mine.
I look forward to seeing these multiple benefits of ore sorting reflected in our combined Tower and Rail PEA which is currently underway."
Ore Sorting Update for Tower and Rail Deposits
Coarse crushed samples from Rockcliff's Tower and Rail deposits were selected by hand from five near surface diamond drill holes at Base Met Labs in Kamloops, BC and sent for sorting amenability testing at the Steinert facility in Kentucky. About 400 individual samples were selected to represent both local host rock (waste/dilution) and the mineralized target areas across the two deposits. The calculated grade of the combined fragments by deposit is reasonable for this test work when compared to the current indicated resource grade as seen in Table 1 below:
Table 1: Sorting Feed Grades Compared to Resource Estimates
| Assays (%, g/t) | |||
| Cu% | Zn% | Aug/t | |
| Tower Indicated Resource | 4.69 | 1.32 | 0.85 |
| Tower Sorting Sample | 5.83 | 1.09 | 0.79 |
| Rail Indicated Resource | 2.73 | 0.86 | 0.80 |
| Rail Sorting Sample | 1.53 | 0.60 | 0.71 |
The individual fragments ranged in size from 10 mm to 40 mm and each piece was initially scanned prior to a scoping level bulk sorting demonstration using X-ray transmission ("XT") technology. The advantage of using XT for the ore sort is that this sorting technique requires very little material preparation and is insensitive to moisture or dust coatings on the particles.
A preliminary bulk sorting demonstration was also completed for each deposit. The sorting test was conducted in two stages: first at a high sensitivity to generate a high-grade, low mass concentrate and second at a lower sensitivity to capture the residual sulphide material in the sample. For Tower, over 99% of the metals were recovered to 67% of the mass, and for Rail over 98% of the metals were recovered to 68% of the mass. The results, showing the grades of the concentrate and the rejects, are summarized in the Table 2 below. Metal grades at both deposits were increased by almost 50% from expected mining diluted grades. The mass balances suggest that sulphide material was pulled into the concentrate from the host/dilution rock and that non-sulphide material was rejected to the waste stream from within the mineralized envelope. Sorting technology has strong potential for industrial application to upgrade mined Tower and Rail material prior to transport to the mill. This will benefit both projects through rejection of low value waste or mine dilution and lower overall transportation costs with better mill feed grades all contributing to improved project economics.
Table 2: Ore Sorting Upgrade Results
| Tower | ||||||||||
| Mass | Assays (%, g/t) | Distribution (%) | ||||||||
| (%) | Cu | Zn | Au | S | Cu | Zn | Au | S | ||
| Combined Accepts | 67 | 8.6 | 1.62 | 1.2 | 17.8 | 99.3 | 99.4 | 99.2 | 96.9 | |
| Rejects | 33 | 0.13 | 0.02 | 0.02 | 1.15 | 0.7 | 0.6 | 0.8 | 3.1 | |
| Total | 100 | 5.83 | 1.09 | 0.8 | 12.3 | 100 | 100 | 100 | 100 | |
| Upgrade Ratio | 1.48 | 1.49 | 1.46 | 1.45 | ||||||
| Rail | ||||||||||
| Mass | Assays (%, g/t) | Distribution (%) | ||||||||
| (%) | Cu | Zn | Au | S | Cu | Zn | Au | S | ||
| Combine Accepts | 68.3 | 2.2 | 0.86 | 1.0 | 12.2 | 98.7 | 98.4 | 98.6 | 98.3 | |
| Rejects | 31.7 | 0.06 | 0.03 | 0.03 | 0.46 | 1.3 | 1.6 | 1.4 | 1.7 | |
| Total | 100 | 1.52 | 0.59 | 0.7 | 8.5 | 100 | 100 | 100 | 100 | |
| Upgrade Ratio | 1.45 | 1.46 | 1.46 | 1.44 | ||||||
Summarized indicative impacts from the ore sorting test results above on the Tower and Rails deposit are as follows:
Tower Deposit
| Cu | Zn | Au | Ag | ||
| tonnes | % | % | g/t | g/t | |
| In-situ Indicated resource grade1 | 1,500 | 4.69 | 1.32 | 0.85 | 23.70 |
| Diluted mine grade (to ore sorter) | 2,000 | 3.52 | 0.99 | 0.64 | 17.78 |
| Grade shipped to mill | 1,345 | 5.19 | 1.46 | 0.94 | 26.20 |
| Feed grade to mill upgrade from diluted mine grade | 1.48x | 1.48x | 1.47x | 1.47x |
1 Grades based on the N.I. 43-101 Tower Resource Resource estimate published March 2, 2020
Rail Deposit
| Cu | Zn | Au | Ag | ||
| tonnes | % | % | g/t | g/t | |
| In-situ Indicated resource grade 2 | 1,500 | 2.73 | 0.86 | 0.80 | 8.90 |
| Diluted mine grade (to ore sorter) | 2,000 | 2.05 | 0.65 | 0.60 | 6.68 |
| Grade shipped to mill | 1,363 | 2.97 | 0.93 | 0.87 | 9.66 |
| Feed grade to mill upgrade from diluted mine grade | 1.45x | 1.44x | 1.45x | 1.45x |
2 Grades based on the N.I. 43-101 Rail Resource Resource estimate published March 31, 2020
Milling Permits and Metallurgical Studies
Rockcliff has a six year lease on the Bucko Mill and tailings facilty located within trucking distance from its portfolio of Snow Lake deposits.
Metallurgical test work has been designed in two phases. The first phase has demonstrated the ability of the ore to respond to concentration by flotation. The second phase will focus on the optimization of the concentration process through the Bucko Mill. This will enable Rockcliff to evaluate the potential of mill upgrades and the economic trade-off of capital required for this optimization. The phase II work schedule has begun and is to be completed as part of the PEA studies for the Rail and Tower properties anticipated to be completed in Q3 2020 in anticipation for a construction decision on one of the two deposits.
QP
Mike Romaniuk P.Eng., VP Projects of Rockcliff, a Qualified Person in accordance with Canadian regulatory requirements as set out in NI 43-101, has read and approved the scientific and technical information that forms the basis for the disclosure contained in this press release.
Visit Rockcliff's YouTube channel with a message from the President and CEO, Alistair Ross. To access the video, please visit: https://youtu.be/11cJFoZLduE.
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About Rockcliff Metals Corporation
Rockcliff is a well-funded Canadian resource development and exploration company, with a fully functional +1,000 tpd leased processing and tailings facility as well as several advance-staged, high-grade copper and zinc dominant VMS deposits in the Snow Lake area of central Manitoba. The Company is a major landholder in the Flin Flon-Snow Lake greenstone belt which is home to the largest Paleoproterozoic Volcanogenic Massive Sulphide ("VMS") district in the world, hosting mines and deposits containing copper, zinc, gold and silver. The Company's extensive portfolio of properties totals over 4,500 square kilometres and includes eight of the highest-grade, undeveloped VMS deposits in the belt.
For more information, please visit http://rockcliffmetals.com
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For further information, please contact:
Rockcliff Metals Corporation
Alistair Ross
President & CEO
Cell: (249) 805-9020
contact@rockcliffmetals.com
Cautionary Note Regarding Forward-Looking Statements: This news release includes forward-looking statements that are subject to risks and uncertainties. Forward-looking statements involve known and unknown risks, uncertainties, and other factors that could cause the actual results of the Company to be materially different from the historical results or from any future results expressed or implied by such forward-looking statements. All statements contained in this news release, other than statements of historical fact, are to be considered forward-looking. Although Rockcliff believes the expectations expressed in such forward-looking statements are based on reasonable assumptions, such statements are not a guarantee of future performance and actual results or developments may differ materially from those in the forward-looking statements.
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